ent/doc: add edge example for o2o 2 types

Reviewed By: alexsn

Differential Revision: D17045287

fbshipit-source-id: e62bce8c1935b844aa26712bb9dc574b525a275c

examples/o2o2types/README.md

@@ -0,0 +1,10 @@
+# User-Card O2O Relation Example
+
+An example for a O2O relation between a User and Card.  
+In the example, a User can have only one card, and a card must have exactly one owner (required edge).
+
+### Generate Assets
+
+```console
+go generate ./...
+```

examples/o2o2types/ent/card.go

@@ -0,0 +1,98 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"bytes"
+	"fmt"
+	"time"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// Card is the model entity for the Card schema.
+type Card struct {
+	config
+	// ID of the ent.
+	ID int `json:"id,omitempty"`
+	// Expired holds the value of the "expired" field.
+	Expired time.Time `json:"expired,omitempty"`
+	// Number holds the value of the "number" field.
+	Number string `json:"number,omitempty"`
+}
+
+// FromRows scans the sql response data into Card.
+func (c *Card) FromRows(rows *sql.Rows) error {
+	var vc struct {
+		ID      int
+		Expired sql.NullTime
+		Number  sql.NullString
+	}
+	// the order here should be the same as in the `card.Columns`.
+	if err := rows.Scan(
+		&vc.ID,
+		&vc.Expired,
+		&vc.Number,
+	); err != nil {
+		return err
+	}
+	c.ID = vc.ID
+	c.Expired = vc.Expired.Time
+	c.Number = vc.Number.String
+	return nil
+}
+
+// QueryOwner queries the owner edge of the Card.
+func (c *Card) QueryOwner() *UserQuery {
+	return (&CardClient{c.config}).QueryOwner(c)
+}
+
+// Update returns a builder for updating this Card.
+// Note that, you need to call Card.Unwrap() before calling this method, if this Card
+// was returned from a transaction, and the transaction was committed or rolled back.
+func (c *Card) Update() *CardUpdateOne {
+	return (&CardClient{c.config}).UpdateOne(c)
+}
+
+// Unwrap unwraps the entity that was returned from a transaction after it was closed,
+// so that all next queries will be executed through the driver which created the transaction.
+func (c *Card) Unwrap() *Card {
+	tx, ok := c.config.driver.(*txDriver)
+	if !ok {
+		panic("ent: Card is not a transactional entity")
+	}
+	c.config.driver = tx.drv
+	return c
+}
+
+// String implements the fmt.Stringer.
+func (c *Card) String() string {
+	buf := bytes.NewBuffer(nil)
+	buf.WriteString("Card(")
+	buf.WriteString(fmt.Sprintf("id=%v", c.ID))
+	buf.WriteString(fmt.Sprintf(", expired=%v", c.Expired))
+	buf.WriteString(fmt.Sprintf(", number=%v", c.Number))
+	buf.WriteString(")")
+	return buf.String()
+}
+
+// Cards is a parsable slice of Card.
+type Cards []*Card
+
+// FromRows scans the sql response data into Cards.
+func (c *Cards) FromRows(rows *sql.Rows) error {
+	for rows.Next() {
+		vc := &Card{}
+		if err := vc.FromRows(rows); err != nil {
+			return err
+		}
+		*c = append(*c, vc)
+	}
+	return nil
+}
+
+func (c Cards) config(cfg config) {
+	for i := range c {
+		c[i].config = cfg
+	}
+}

examples/o2o2types/ent/card/card.go

@@ -0,0 +1,31 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package card
+
+const (
+	// Label holds the string label denoting the card type in the database.
+	Label = "card"
+	// FieldID holds the string denoting the id field in the database.
+	FieldID = "id"
+	// FieldExpired holds the string denoting the expired vertex property in the database.
+	FieldExpired = "expired"
+	// FieldNumber holds the string denoting the number vertex property in the database.
+	FieldNumber = "number"
+
+	// Table holds the table name of the card in the database.
+	Table = "cards"
+	// OwnerTable is the table the holds the owner relation/edge.
+	OwnerTable = "cards"
+	// OwnerInverseTable is the table name for the User entity.
+	// It exists in this package in order to avoid circular dependency with the "user" package.
+	OwnerInverseTable = "users"
+	// OwnerColumn is the table column denoting the owner relation/edge.
+	OwnerColumn = "owner_id"
+)
+
+// Columns holds all SQL columns are card fields.
+var Columns = []string{
+	FieldID,
+	FieldExpired,
+	FieldNumber,
+}

examples/o2o2types/ent/card/where.go

@@ -0,0 +1,408 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package card
+
+import (
+	"time"
+
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/predicate"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// ID filters vertices based on their identifier.
+func ID(id int) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.EQ(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDEQ applies the EQ predicate on the ID field.
+func IDEQ(id int) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.EQ(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDNEQ applies the NEQ predicate on the ID field.
+func IDNEQ(id int) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.NEQ(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDGT applies the GT predicate on the ID field.
+func IDGT(id int) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.GT(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDGTE applies the GTE predicate on the ID field.
+func IDGTE(id int) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.GTE(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDLT applies the LT predicate on the ID field.
+func IDLT(id int) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.LT(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDLTE applies the LTE predicate on the ID field.
+func IDLTE(id int) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.LTE(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDIn applies the In predicate on the ID field.
+func IDIn(ids ...int) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			// if not arguments were provided, append the FALSE constants,
+			// since we can't apply "IN ()". This will make this predicate falsy.
+			if len(ids) == 0 {
+				s.Where(sql.False())
+				return
+			}
+			v := make([]interface{}, len(ids))
+			for i := range v {
+				v[i] = ids[i]
+			}
+			s.Where(sql.In(s.C(FieldID), v...))
+		},
+	)
+}
+
+// IDNotIn applies the NotIn predicate on the ID field.
+func IDNotIn(ids ...int) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			// if not arguments were provided, append the FALSE constants,
+			// since we can't apply "IN ()". This will make this predicate falsy.
+			if len(ids) == 0 {
+				s.Where(sql.False())
+				return
+			}
+			v := make([]interface{}, len(ids))
+			for i := range v {
+				v[i] = ids[i]
+			}
+			s.Where(sql.NotIn(s.C(FieldID), v...))
+		},
+	)
+}
+
+// Expired applies equality check predicate on the "expired" field. It's identical to ExpiredEQ.
+func Expired(v time.Time) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.EQ(s.C(FieldExpired), v))
+		},
+	)
+}
+
+// Number applies equality check predicate on the "number" field. It's identical to NumberEQ.
+func Number(v string) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.EQ(s.C(FieldNumber), v))
+		},
+	)
+}
+
+// ExpiredEQ applies the EQ predicate on the "expired" field.
+func ExpiredEQ(v time.Time) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.EQ(s.C(FieldExpired), v))
+		},
+	)
+}
+
+// ExpiredNEQ applies the NEQ predicate on the "expired" field.
+func ExpiredNEQ(v time.Time) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.NEQ(s.C(FieldExpired), v))
+		},
+	)
+}
+
+// ExpiredGT applies the GT predicate on the "expired" field.
+func ExpiredGT(v time.Time) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.GT(s.C(FieldExpired), v))
+		},
+	)
+}
+
+// ExpiredGTE applies the GTE predicate on the "expired" field.
+func ExpiredGTE(v time.Time) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.GTE(s.C(FieldExpired), v))
+		},
+	)
+}
+
+// ExpiredLT applies the LT predicate on the "expired" field.
+func ExpiredLT(v time.Time) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.LT(s.C(FieldExpired), v))
+		},
+	)
+}
+
+// ExpiredLTE applies the LTE predicate on the "expired" field.
+func ExpiredLTE(v time.Time) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.LTE(s.C(FieldExpired), v))
+		},
+	)
+}
+
+// ExpiredIn applies the In predicate on the "expired" field.
+func ExpiredIn(vs ...time.Time) predicate.Card {
+	v := make([]interface{}, len(vs))
+	for i := range v {
+		v[i] = vs[i]
+	}
+	return predicate.Card(
+		func(s *sql.Selector) {
+			// if not arguments were provided, append the FALSE constants,
+			// since we can't apply "IN ()". This will make this predicate falsy.
+			if len(vs) == 0 {
+				s.Where(sql.False())
+				return
+			}
+			s.Where(sql.In(s.C(FieldExpired), v...))
+		},
+	)
+}
+
+// ExpiredNotIn applies the NotIn predicate on the "expired" field.
+func ExpiredNotIn(vs ...time.Time) predicate.Card {
+	v := make([]interface{}, len(vs))
+	for i := range v {
+		v[i] = vs[i]
+	}
+	return predicate.Card(
+		func(s *sql.Selector) {
+			// if not arguments were provided, append the FALSE constants,
+			// since we can't apply "IN ()". This will make this predicate falsy.
+			if len(vs) == 0 {
+				s.Where(sql.False())
+				return
+			}
+			s.Where(sql.NotIn(s.C(FieldExpired), v...))
+		},
+	)
+}
+
+// NumberEQ applies the EQ predicate on the "number" field.
+func NumberEQ(v string) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.EQ(s.C(FieldNumber), v))
+		},
+	)
+}
+
+// NumberNEQ applies the NEQ predicate on the "number" field.
+func NumberNEQ(v string) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.NEQ(s.C(FieldNumber), v))
+		},
+	)
+}
+
+// NumberGT applies the GT predicate on the "number" field.
+func NumberGT(v string) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.GT(s.C(FieldNumber), v))
+		},
+	)
+}
+
+// NumberGTE applies the GTE predicate on the "number" field.
+func NumberGTE(v string) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.GTE(s.C(FieldNumber), v))
+		},
+	)
+}
+
+// NumberLT applies the LT predicate on the "number" field.
+func NumberLT(v string) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.LT(s.C(FieldNumber), v))
+		},
+	)
+}
+
+// NumberLTE applies the LTE predicate on the "number" field.
+func NumberLTE(v string) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.LTE(s.C(FieldNumber), v))
+		},
+	)
+}
+
+// NumberIn applies the In predicate on the "number" field.
+func NumberIn(vs ...string) predicate.Card {
+	v := make([]interface{}, len(vs))
+	for i := range v {
+		v[i] = vs[i]
+	}
+	return predicate.Card(
+		func(s *sql.Selector) {
+			// if not arguments were provided, append the FALSE constants,
+			// since we can't apply "IN ()". This will make this predicate falsy.
+			if len(vs) == 0 {
+				s.Where(sql.False())
+				return
+			}
+			s.Where(sql.In(s.C(FieldNumber), v...))
+		},
+	)
+}
+
+// NumberNotIn applies the NotIn predicate on the "number" field.
+func NumberNotIn(vs ...string) predicate.Card {
+	v := make([]interface{}, len(vs))
+	for i := range v {
+		v[i] = vs[i]
+	}
+	return predicate.Card(
+		func(s *sql.Selector) {
+			// if not arguments were provided, append the FALSE constants,
+			// since we can't apply "IN ()". This will make this predicate falsy.
+			if len(vs) == 0 {
+				s.Where(sql.False())
+				return
+			}
+			s.Where(sql.NotIn(s.C(FieldNumber), v...))
+		},
+	)
+}
+
+// NumberContains applies the Contains predicate on the "number" field.
+func NumberContains(v string) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.Contains(s.C(FieldNumber), v))
+		},
+	)
+}
+
+// NumberHasPrefix applies the HasPrefix predicate on the "number" field.
+func NumberHasPrefix(v string) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.HasPrefix(s.C(FieldNumber), v))
+		},
+	)
+}
+
+// NumberHasSuffix applies the HasSuffix predicate on the "number" field.
+func NumberHasSuffix(v string) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.HasSuffix(s.C(FieldNumber), v))
+		},
+	)
+}
+
+// NumberContainsFold applies the ContainsFold predicate on the "number" field.
+func NumberContainsFold(v string) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			s.Where(sql.ContainsFold(s.C(FieldNumber), v))
+		},
+	)
+}
+
+// HasOwner applies the HasEdge predicate on the "owner" edge.
+func HasOwner() predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			t1 := s.Table()
+			s.Where(sql.NotNull(t1.C(OwnerColumn)))
+		},
+	)
+}
+
+// HasOwnerWith applies the HasEdge predicate on the "owner" edge with a given conditions (other predicates).
+func HasOwnerWith(preds ...predicate.User) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			t1 := s.Table()
+			t2 := sql.Select(FieldID).From(sql.Table(OwnerInverseTable))
+			for _, p := range preds {
+				p(t2)
+			}
+			s.Where(sql.In(t1.C(OwnerColumn), t2))
+		},
+	)
+}
+
+// And groups list of predicates with the AND operator between them.
+func And(predicates ...predicate.Card) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			for _, p := range predicates {
+				p(s)
+			}
+		},
+	)
+}
+
+// Or groups list of predicates with the OR operator between them.
+func Or(predicates ...predicate.Card) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			for i, p := range predicates {
+				if i > 0 {
+					s.Or()
+				}
+				p(s)
+			}
+		},
+	)
+}
+
+// Not applies the not operator on the given predicate.
+func Not(p predicate.Card) predicate.Card {
+	return predicate.Card(
+		func(s *sql.Selector) {
+			p(s.Not())
+		},
+	)
+}

examples/o2o2types/ent/card_create.go

@@ -0,0 +1,124 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/card"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// CardCreate is the builder for creating a Card entity.
+type CardCreate struct {
+	config
+	expired *time.Time
+	number  *string
+	owner   map[int]struct{}
+}
+
+// SetExpired sets the expired field.
+func (cc *CardCreate) SetExpired(t time.Time) *CardCreate {
+	cc.expired = &t
+	return cc
+}
+
+// SetNumber sets the number field.
+func (cc *CardCreate) SetNumber(s string) *CardCreate {
+	cc.number = &s
+	return cc
+}
+
+// SetOwnerID sets the owner edge to User by id.
+func (cc *CardCreate) SetOwnerID(id int) *CardCreate {
+	if cc.owner == nil {
+		cc.owner = make(map[int]struct{})
+	}
+	cc.owner[id] = struct{}{}
+	return cc
+}
+
+// SetOwner sets the owner edge to User.
+func (cc *CardCreate) SetOwner(u *User) *CardCreate {
+	return cc.SetOwnerID(u.ID)
+}
+
+// Save creates the Card in the database.
+func (cc *CardCreate) Save(ctx context.Context) (*Card, error) {
+	if cc.expired == nil {
+		return nil, errors.New("ent: missing required field \"expired\"")
+	}
+	if cc.number == nil {
+		return nil, errors.New("ent: missing required field \"number\"")
+	}
+	if len(cc.owner) > 1 {
+		return nil, errors.New("ent: multiple assignments on a unique edge \"owner\"")
+	}
+	if cc.owner == nil {
+		return nil, errors.New("ent: missing required edge \"owner\"")
+	}
+	return cc.sqlSave(ctx)
+}
+
+// SaveX calls Save and panics if Save returns an error.
+func (cc *CardCreate) SaveX(ctx context.Context) *Card {
+	v, err := cc.Save(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+func (cc *CardCreate) sqlSave(ctx context.Context) (*Card, error) {
+	var (
+		res sql.Result
+		c   = &Card{config: cc.config}
+	)
+	tx, err := cc.driver.Tx(ctx)
+	if err != nil {
+		return nil, err
+	}
+	builder := sql.Insert(card.Table).Default(cc.driver.Dialect())
+	if cc.expired != nil {
+		builder.Set(card.FieldExpired, *cc.expired)
+		c.Expired = *cc.expired
+	}
+	if cc.number != nil {
+		builder.Set(card.FieldNumber, *cc.number)
+		c.Number = *cc.number
+	}
+	query, args := builder.Query()
+	if err := tx.Exec(ctx, query, args, &res); err != nil {
+		return nil, rollback(tx, err)
+	}
+	id, err := res.LastInsertId()
+	if err != nil {
+		return nil, rollback(tx, err)
+	}
+	c.ID = int(id)
+	if len(cc.owner) > 0 {
+		eid := keys(cc.owner)[0]
+		query, args := sql.Update(card.OwnerTable).
+			Set(card.OwnerColumn, eid).
+			Where(sql.EQ(card.FieldID, id).And().IsNull(card.OwnerColumn)).
+			Query()
+		if err := tx.Exec(ctx, query, args, &res); err != nil {
+			return nil, rollback(tx, err)
+		}
+		affected, err := res.RowsAffected()
+		if err != nil {
+			return nil, rollback(tx, err)
+		}
+		if int(affected) < len(cc.owner) {
+			return nil, rollback(tx, &ErrConstraintFailed{msg: fmt.Sprintf("one of \"owner\" %v already connected to a different \"Card\"", keys(cc.owner))})
+		}
+	}
+	if err := tx.Commit(); err != nil {
+		return nil, err
+	}
+	return c, nil
+}

examples/o2o2types/ent/card_delete.go

@@ -0,0 +1,61 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/card"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/predicate"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// CardDelete is the builder for deleting a Card entity.
+type CardDelete struct {
+	config
+	predicates []predicate.Card
+}
+
+// Where adds a new predicate for the builder.
+func (cd *CardDelete) Where(ps ...predicate.Card) *CardDelete {
+	cd.predicates = append(cd.predicates, ps...)
+	return cd
+}
+
+// Exec executes the deletion query.
+func (cd *CardDelete) Exec(ctx context.Context) error {
+	return cd.sqlExec(ctx)
+}
+
+// ExecX is like Exec, but panics if an error occurs.
+func (cd *CardDelete) ExecX(ctx context.Context) {
+	if err := cd.Exec(ctx); err != nil {
+		panic(err)
+	}
+}
+
+func (cd *CardDelete) sqlExec(ctx context.Context) error {
+	var res sql.Result
+	selector := sql.Select().From(sql.Table(card.Table))
+	for _, p := range cd.predicates {
+		p(selector)
+	}
+	query, args := sql.Delete(card.Table).FromSelect(selector).Query()
+	return cd.driver.Exec(ctx, query, args, &res)
+}
+
+// CardDeleteOne is the builder for deleting a single Card entity.
+type CardDeleteOne struct {
+	cd *CardDelete
+}
+
+// Exec executes the deletion query.
+func (cdo *CardDeleteOne) Exec(ctx context.Context) error {
+	return cdo.cd.Exec(ctx)
+}
+
+// ExecX is like Exec, but panics if an error occurs.
+func (cdo *CardDeleteOne) ExecX(ctx context.Context) {
+	cdo.cd.ExecX(ctx)
+}

examples/o2o2types/ent/card_query.go

@@ -0,0 +1,483 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"math"
+
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/card"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/predicate"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/user"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// CardQuery is the builder for querying Card entities.
+type CardQuery struct {
+	config
+	limit      *int
+	offset     *int
+	order      []Order
+	unique     []string
+	predicates []predicate.Card
+	// intermediate queries.
+	sql *sql.Selector
+}
+
+// Where adds a new predicate for the builder.
+func (cq *CardQuery) Where(ps ...predicate.Card) *CardQuery {
+	cq.predicates = append(cq.predicates, ps...)
+	return cq
+}
+
+// Limit adds a limit step to the query.
+func (cq *CardQuery) Limit(limit int) *CardQuery {
+	cq.limit = &limit
+	return cq
+}
+
+// Offset adds an offset step to the query.
+func (cq *CardQuery) Offset(offset int) *CardQuery {
+	cq.offset = &offset
+	return cq
+}
+
+// Order adds an order step to the query.
+func (cq *CardQuery) Order(o ...Order) *CardQuery {
+	cq.order = append(cq.order, o...)
+	return cq
+}
+
+// QueryOwner chains the current query on the owner edge.
+func (cq *CardQuery) QueryOwner() *UserQuery {
+	query := &UserQuery{config: cq.config}
+	t1 := sql.Table(user.Table)
+	t2 := cq.sqlQuery()
+	t2.Select(t2.C(card.OwnerColumn))
+	query.sql = sql.Select(t1.Columns(user.Columns...)...).
+		From(t1).
+		Join(t2).
+		On(t1.C(user.FieldID), t2.C(card.OwnerColumn))
+	return query
+}
+
+// Get returns a Card entity by its id.
+func (cq *CardQuery) Get(ctx context.Context, id int) (*Card, error) {
+	return cq.Where(card.ID(id)).Only(ctx)
+}
+
+// GetX is like Get, but panics if an error occurs.
+func (cq *CardQuery) GetX(ctx context.Context, id int) *Card {
+	c, err := cq.Get(ctx, id)
+	if err != nil {
+		panic(err)
+	}
+	return c
+}
+
+// First returns the first Card entity in the query. Returns *ErrNotFound when no card was found.
+func (cq *CardQuery) First(ctx context.Context) (*Card, error) {
+	cs, err := cq.Limit(1).All(ctx)
+	if err != nil {
+		return nil, err
+	}
+	if len(cs) == 0 {
+		return nil, &ErrNotFound{card.Label}
+	}
+	return cs[0], nil
+}
+
+// FirstX is like First, but panics if an error occurs.
+func (cq *CardQuery) FirstX(ctx context.Context) *Card {
+	c, err := cq.First(ctx)
+	if err != nil && !IsNotFound(err) {
+		panic(err)
+	}
+	return c
+}
+
+// FirstID returns the first Card id in the query. Returns *ErrNotFound when no id was found.
+func (cq *CardQuery) FirstID(ctx context.Context) (id int, err error) {
+	var ids []int
+	if ids, err = cq.Limit(1).IDs(ctx); err != nil {
+		return
+	}
+	if len(ids) == 0 {
+		err = &ErrNotFound{card.Label}
+		return
+	}
+	return ids[0], nil
+}
+
+// FirstXID is like FirstID, but panics if an error occurs.
+func (cq *CardQuery) FirstXID(ctx context.Context) int {
+	id, err := cq.FirstID(ctx)
+	if err != nil && !IsNotFound(err) {
+		panic(err)
+	}
+	return id
+}
+
+// Only returns the only Card entity in the query, returns an error if not exactly one entity was returned.
+func (cq *CardQuery) Only(ctx context.Context) (*Card, error) {
+	cs, err := cq.Limit(2).All(ctx)
+	if err != nil {
+		return nil, err
+	}
+	switch len(cs) {
+	case 1:
+		return cs[0], nil
+	case 0:
+		return nil, &ErrNotFound{card.Label}
+	default:
+		return nil, &ErrNotSingular{card.Label}
+	}
+}
+
+// OnlyX is like Only, but panics if an error occurs.
+func (cq *CardQuery) OnlyX(ctx context.Context) *Card {
+	c, err := cq.Only(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return c
+}
+
+// OnlyID returns the only Card id in the query, returns an error if not exactly one id was returned.
+func (cq *CardQuery) OnlyID(ctx context.Context) (id int, err error) {
+	var ids []int
+	if ids, err = cq.Limit(2).IDs(ctx); err != nil {
+		return
+	}
+	switch len(ids) {
+	case 1:
+		id = ids[0]
+	case 0:
+		err = &ErrNotFound{card.Label}
+	default:
+		err = &ErrNotSingular{card.Label}
+	}
+	return
+}
+
+// OnlyXID is like OnlyID, but panics if an error occurs.
+func (cq *CardQuery) OnlyXID(ctx context.Context) int {
+	id, err := cq.OnlyID(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return id
+}
+
+// All executes the query and returns a list of Cards.
+func (cq *CardQuery) All(ctx context.Context) ([]*Card, error) {
+	return cq.sqlAll(ctx)
+}
+
+// AllX is like All, but panics if an error occurs.
+func (cq *CardQuery) AllX(ctx context.Context) []*Card {
+	cs, err := cq.All(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return cs
+}
+
+// IDs executes the query and returns a list of Card ids.
+func (cq *CardQuery) IDs(ctx context.Context) ([]int, error) {
+	return cq.sqlIDs(ctx)
+}
+
+// IDsX is like IDs, but panics if an error occurs.
+func (cq *CardQuery) IDsX(ctx context.Context) []int {
+	ids, err := cq.IDs(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return ids
+}
+
+// Count returns the count of the given query.
+func (cq *CardQuery) Count(ctx context.Context) (int, error) {
+	return cq.sqlCount(ctx)
+}
+
+// CountX is like Count, but panics if an error occurs.
+func (cq *CardQuery) CountX(ctx context.Context) int {
+	count, err := cq.Count(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return count
+}
+
+// Exist returns true if the query has elements in the graph.
+func (cq *CardQuery) Exist(ctx context.Context) (bool, error) {
+	return cq.sqlExist(ctx)
+}
+
+// ExistX is like Exist, but panics if an error occurs.
+func (cq *CardQuery) ExistX(ctx context.Context) bool {
+	exist, err := cq.Exist(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return exist
+}
+
+// Clone returns a duplicate of the query builder, including all associated steps. It can be
+// used to prepare common query builders and use them differently after the clone is made.
+func (cq *CardQuery) Clone() *CardQuery {
+	return &CardQuery{
+		config:     cq.config,
+		limit:      cq.limit,
+		offset:     cq.offset,
+		order:      append([]Order{}, cq.order...),
+		unique:     append([]string{}, cq.unique...),
+		predicates: append([]predicate.Card{}, cq.predicates...),
+		// clone intermediate queries.
+		sql: cq.sql.Clone(),
+	}
+}
+
+// GroupBy used to group vertices by one or more fields/columns.
+// It is often used with aggregate functions, like: count, max, mean, min, sum.
+//
+// Example:
+//
+//	var v []struct {
+//		Expired time.Time `json:"expired,omitempty"`
+//		Count int `json:"count,omitempty"`
+//	}
+//
+//	client.Card.Query().
+//		GroupBy(card.FieldExpired).
+//		Aggregate(ent.Count()).
+//		Scan(ctx, &v)
+//
+func (cq *CardQuery) GroupBy(field string, fields ...string) *CardGroupBy {
+	group := &CardGroupBy{config: cq.config}
+	group.fields = append([]string{field}, fields...)
+	group.sql = cq.sqlQuery()
+	return group
+}
+
+func (cq *CardQuery) sqlAll(ctx context.Context) ([]*Card, error) {
+	rows := &sql.Rows{}
+	selector := cq.sqlQuery()
+	if unique := cq.unique; len(unique) == 0 {
+		selector.Distinct()
+	}
+	query, args := selector.Query()
+	if err := cq.driver.Query(ctx, query, args, rows); err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var cs Cards
+	if err := cs.FromRows(rows); err != nil {
+		return nil, err
+	}
+	cs.config(cq.config)
+	return cs, nil
+}
+
+func (cq *CardQuery) sqlCount(ctx context.Context) (int, error) {
+	rows := &sql.Rows{}
+	selector := cq.sqlQuery()
+	unique := []string{card.FieldID}
+	if len(cq.unique) > 0 {
+		unique = cq.unique
+	}
+	selector.Count(sql.Distinct(selector.Columns(unique...)...))
+	query, args := selector.Query()
+	if err := cq.driver.Query(ctx, query, args, rows); err != nil {
+		return 0, err
+	}
+	defer rows.Close()
+	if !rows.Next() {
+		return 0, errors.New("ent: no rows found")
+	}
+	var n int
+	if err := rows.Scan(&n); err != nil {
+		return 0, fmt.Errorf("ent: failed reading count: %v", err)
+	}
+	return n, nil
+}
+
+func (cq *CardQuery) sqlExist(ctx context.Context) (bool, error) {
+	n, err := cq.sqlCount(ctx)
+	if err != nil {
+		return false, fmt.Errorf("ent: check existence: %v", err)
+	}
+	return n > 0, nil
+}
+
+func (cq *CardQuery) sqlIDs(ctx context.Context) ([]int, error) {
+	vs, err := cq.sqlAll(ctx)
+	if err != nil {
+		return nil, err
+	}
+	var ids []int
+	for _, v := range vs {
+		ids = append(ids, v.ID)
+	}
+	return ids, nil
+}
+
+func (cq *CardQuery) sqlQuery() *sql.Selector {
+	t1 := sql.Table(card.Table)
+	selector := sql.Select(t1.Columns(card.Columns...)...).From(t1)
+	if cq.sql != nil {
+		selector = cq.sql
+		selector.Select(selector.Columns(card.Columns...)...)
+	}
+	for _, p := range cq.predicates {
+		p(selector)
+	}
+	for _, p := range cq.order {
+		p(selector)
+	}
+	if offset := cq.offset; offset != nil {
+		// limit is mandatory for offset clause. We start
+		// with default value, and override it below if needed.
+		selector.Offset(*offset).Limit(math.MaxInt64)
+	}
+	if limit := cq.limit; limit != nil {
+		selector.Limit(*limit)
+	}
+	return selector
+}
+
+// CardQuery is the builder for group-by Card entities.
+type CardGroupBy struct {
+	config
+	fields []string
+	fns    []Aggregate
+	// intermediate queries.
+	sql *sql.Selector
+}
+
+// Aggregate adds the given aggregation functions to the group-by query.
+func (cgb *CardGroupBy) Aggregate(fns ...Aggregate) *CardGroupBy {
+	cgb.fns = append(cgb.fns, fns...)
+	return cgb
+}
+
+// Scan applies the group-by query and scan the result into the given value.
+func (cgb *CardGroupBy) Scan(ctx context.Context, v interface{}) error {
+	return cgb.sqlScan(ctx, v)
+}
+
+// ScanX is like Scan, but panics if an error occurs.
+func (cgb *CardGroupBy) ScanX(ctx context.Context, v interface{}) {
+	if err := cgb.Scan(ctx, v); err != nil {
+		panic(err)
+	}
+}
+
+// Strings returns list of strings from group-by. It is only allowed when querying group-by with one field.
+func (cgb *CardGroupBy) Strings(ctx context.Context) ([]string, error) {
+	if len(cgb.fields) > 1 {
+		return nil, errors.New("ent: CardGroupBy.Strings is not achievable when grouping more than 1 field")
+	}
+	var v []string
+	if err := cgb.Scan(ctx, &v); err != nil {
+		return nil, err
+	}
+	return v, nil
+}
+
+// StringsX is like Strings, but panics if an error occurs.
+func (cgb *CardGroupBy) StringsX(ctx context.Context) []string {
+	v, err := cgb.Strings(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+// Ints returns list of ints from group-by. It is only allowed when querying group-by with one field.
+func (cgb *CardGroupBy) Ints(ctx context.Context) ([]int, error) {
+	if len(cgb.fields) > 1 {
+		return nil, errors.New("ent: CardGroupBy.Ints is not achievable when grouping more than 1 field")
+	}
+	var v []int
+	if err := cgb.Scan(ctx, &v); err != nil {
+		return nil, err
+	}
+	return v, nil
+}
+
+// IntsX is like Ints, but panics if an error occurs.
+func (cgb *CardGroupBy) IntsX(ctx context.Context) []int {
+	v, err := cgb.Ints(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+// Float64s returns list of float64s from group-by. It is only allowed when querying group-by with one field.
+func (cgb *CardGroupBy) Float64s(ctx context.Context) ([]float64, error) {
+	if len(cgb.fields) > 1 {
+		return nil, errors.New("ent: CardGroupBy.Float64s is not achievable when grouping more than 1 field")
+	}
+	var v []float64
+	if err := cgb.Scan(ctx, &v); err != nil {
+		return nil, err
+	}
+	return v, nil
+}
+
+// Float64sX is like Float64s, but panics if an error occurs.
+func (cgb *CardGroupBy) Float64sX(ctx context.Context) []float64 {
+	v, err := cgb.Float64s(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+// Bools returns list of bools from group-by. It is only allowed when querying group-by with one field.
+func (cgb *CardGroupBy) Bools(ctx context.Context) ([]bool, error) {
+	if len(cgb.fields) > 1 {
+		return nil, errors.New("ent: CardGroupBy.Bools is not achievable when grouping more than 1 field")
+	}
+	var v []bool
+	if err := cgb.Scan(ctx, &v); err != nil {
+		return nil, err
+	}
+	return v, nil
+}
+
+// BoolsX is like Bools, but panics if an error occurs.
+func (cgb *CardGroupBy) BoolsX(ctx context.Context) []bool {
+	v, err := cgb.Bools(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+func (cgb *CardGroupBy) sqlScan(ctx context.Context, v interface{}) error {
+	rows := &sql.Rows{}
+	query, args := cgb.sqlQuery().Query()
+	if err := cgb.driver.Query(ctx, query, args, rows); err != nil {
+		return err
+	}
+	defer rows.Close()
+	return sql.ScanSlice(rows, v)
+}
+
+func (cgb *CardGroupBy) sqlQuery() *sql.Selector {
+	selector := cgb.sql
+	columns := make([]string, 0, len(cgb.fields)+len(cgb.fns))
+	columns = append(columns, cgb.fields...)
+	for _, fn := range cgb.fns {
+		columns = append(columns, fn.SQL(selector))
+	}
+	return selector.Select(columns...).GroupBy(cgb.fields...)
+}

examples/o2o2types/ent/card_update.go

@@ -0,0 +1,337 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/card"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/predicate"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/user"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// CardUpdate is the builder for updating Card entities.
+type CardUpdate struct {
+	config
+	expired      *time.Time
+	number       *string
+	owner        map[int]struct{}
+	clearedOwner bool
+	predicates   []predicate.Card
+}
+
+// Where adds a new predicate for the builder.
+func (cu *CardUpdate) Where(ps ...predicate.Card) *CardUpdate {
+	cu.predicates = append(cu.predicates, ps...)
+	return cu
+}
+
+// SetExpired sets the expired field.
+func (cu *CardUpdate) SetExpired(t time.Time) *CardUpdate {
+	cu.expired = &t
+	return cu
+}
+
+// SetNumber sets the number field.
+func (cu *CardUpdate) SetNumber(s string) *CardUpdate {
+	cu.number = &s
+	return cu
+}
+
+// SetOwnerID sets the owner edge to User by id.
+func (cu *CardUpdate) SetOwnerID(id int) *CardUpdate {
+	if cu.owner == nil {
+		cu.owner = make(map[int]struct{})
+	}
+	cu.owner[id] = struct{}{}
+	return cu
+}
+
+// SetOwner sets the owner edge to User.
+func (cu *CardUpdate) SetOwner(u *User) *CardUpdate {
+	return cu.SetOwnerID(u.ID)
+}
+
+// ClearOwner clears the owner edge to User.
+func (cu *CardUpdate) ClearOwner() *CardUpdate {
+	cu.clearedOwner = true
+	return cu
+}
+
+// Save executes the query and returns the number of rows/vertices matched by this operation.
+func (cu *CardUpdate) Save(ctx context.Context) (int, error) {
+	if len(cu.owner) > 1 {
+		return 0, errors.New("ent: multiple assignments on a unique edge \"owner\"")
+	}
+	if cu.clearedOwner && cu.owner == nil {
+		return 0, errors.New("ent: clearing a unique edge \"owner\"")
+	}
+	return cu.sqlSave(ctx)
+}
+
+// SaveX is like Save, but panics if an error occurs.
+func (cu *CardUpdate) SaveX(ctx context.Context) int {
+	affected, err := cu.Save(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return affected
+}
+
+// Exec executes the query.
+func (cu *CardUpdate) Exec(ctx context.Context) error {
+	_, err := cu.Save(ctx)
+	return err
+}
+
+// ExecX is like Exec, but panics if an error occurs.
+func (cu *CardUpdate) ExecX(ctx context.Context) {
+	if err := cu.Exec(ctx); err != nil {
+		panic(err)
+	}
+}
+
+func (cu *CardUpdate) sqlSave(ctx context.Context) (n int, err error) {
+	selector := sql.Select(card.FieldID).From(sql.Table(card.Table))
+	for _, p := range cu.predicates {
+		p(selector)
+	}
+	rows := &sql.Rows{}
+	query, args := selector.Query()
+	if err = cu.driver.Query(ctx, query, args, rows); err != nil {
+		return 0, err
+	}
+	defer rows.Close()
+	var ids []int
+	for rows.Next() {
+		var id int
+		if err := rows.Scan(&id); err != nil {
+			return 0, fmt.Errorf("ent: failed reading id: %v", err)
+		}
+		ids = append(ids, id)
+	}
+	if len(ids) == 0 {
+		return 0, nil
+	}
+
+	tx, err := cu.driver.Tx(ctx)
+	if err != nil {
+		return 0, err
+	}
+	var (
+		update  bool
+		res     sql.Result
+		builder = sql.Update(card.Table).Where(sql.InInts(card.FieldID, ids...))
+	)
+	if cu.expired != nil {
+		update = true
+		builder.Set(card.FieldExpired, *cu.expired)
+	}
+	if cu.number != nil {
+		update = true
+		builder.Set(card.FieldNumber, *cu.number)
+	}
+	if update {
+		query, args := builder.Query()
+		if err := tx.Exec(ctx, query, args, &res); err != nil {
+			return 0, rollback(tx, err)
+		}
+	}
+	if cu.clearedOwner {
+		query, args := sql.Update(card.OwnerTable).
+			SetNull(card.OwnerColumn).
+			Where(sql.InInts(user.FieldID, ids...)).
+			Query()
+		if err := tx.Exec(ctx, query, args, &res); err != nil {
+			return 0, rollback(tx, err)
+		}
+	}
+	if len(cu.owner) > 0 {
+		for _, id := range ids {
+			eid := keys(cu.owner)[0]
+			query, args := sql.Update(card.OwnerTable).
+				Set(card.OwnerColumn, eid).
+				Where(sql.EQ(card.FieldID, id).And().IsNull(card.OwnerColumn)).
+				Query()
+			if err := tx.Exec(ctx, query, args, &res); err != nil {
+				return 0, rollback(tx, err)
+			}
+			affected, err := res.RowsAffected()
+			if err != nil {
+				return 0, rollback(tx, err)
+			}
+			if int(affected) < len(cu.owner) {
+				return 0, rollback(tx, &ErrConstraintFailed{msg: fmt.Sprintf("one of \"owner\" %v already connected to a different \"Card\"", keys(cu.owner))})
+			}
+		}
+	}
+	if err = tx.Commit(); err != nil {
+		return 0, err
+	}
+	return len(ids), nil
+}
+
+// CardUpdateOne is the builder for updating a single Card entity.
+type CardUpdateOne struct {
+	config
+	id           int
+	expired      *time.Time
+	number       *string
+	owner        map[int]struct{}
+	clearedOwner bool
+}
+
+// SetExpired sets the expired field.
+func (cuo *CardUpdateOne) SetExpired(t time.Time) *CardUpdateOne {
+	cuo.expired = &t
+	return cuo
+}
+
+// SetNumber sets the number field.
+func (cuo *CardUpdateOne) SetNumber(s string) *CardUpdateOne {
+	cuo.number = &s
+	return cuo
+}
+
+// SetOwnerID sets the owner edge to User by id.
+func (cuo *CardUpdateOne) SetOwnerID(id int) *CardUpdateOne {
+	if cuo.owner == nil {
+		cuo.owner = make(map[int]struct{})
+	}
+	cuo.owner[id] = struct{}{}
+	return cuo
+}
+
+// SetOwner sets the owner edge to User.
+func (cuo *CardUpdateOne) SetOwner(u *User) *CardUpdateOne {
+	return cuo.SetOwnerID(u.ID)
+}
+
+// ClearOwner clears the owner edge to User.
+func (cuo *CardUpdateOne) ClearOwner() *CardUpdateOne {
+	cuo.clearedOwner = true
+	return cuo
+}
+
+// Save executes the query and returns the updated entity.
+func (cuo *CardUpdateOne) Save(ctx context.Context) (*Card, error) {
+	if len(cuo.owner) > 1 {
+		return nil, errors.New("ent: multiple assignments on a unique edge \"owner\"")
+	}
+	if cuo.clearedOwner && cuo.owner == nil {
+		return nil, errors.New("ent: clearing a unique edge \"owner\"")
+	}
+	return cuo.sqlSave(ctx)
+}
+
+// SaveX is like Save, but panics if an error occurs.
+func (cuo *CardUpdateOne) SaveX(ctx context.Context) *Card {
+	c, err := cuo.Save(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return c
+}
+
+// Exec executes the query on the entity.
+func (cuo *CardUpdateOne) Exec(ctx context.Context) error {
+	_, err := cuo.Save(ctx)
+	return err
+}
+
+// ExecX is like Exec, but panics if an error occurs.
+func (cuo *CardUpdateOne) ExecX(ctx context.Context) {
+	if err := cuo.Exec(ctx); err != nil {
+		panic(err)
+	}
+}
+
+func (cuo *CardUpdateOne) sqlSave(ctx context.Context) (c *Card, err error) {
+	selector := sql.Select(card.Columns...).From(sql.Table(card.Table))
+	card.ID(cuo.id)(selector)
+	rows := &sql.Rows{}
+	query, args := selector.Query()
+	if err = cuo.driver.Query(ctx, query, args, rows); err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var ids []int
+	for rows.Next() {
+		var id int
+		c = &Card{config: cuo.config}
+		if err := c.FromRows(rows); err != nil {
+			return nil, fmt.Errorf("ent: failed scanning row into Card: %v", err)
+		}
+		id = c.ID
+		ids = append(ids, id)
+	}
+	switch n := len(ids); {
+	case n == 0:
+		return nil, fmt.Errorf("ent: Card not found with id: %v", cuo.id)
+	case n > 1:
+		return nil, fmt.Errorf("ent: more than one Card with the same id: %v", cuo.id)
+	}
+
+	tx, err := cuo.driver.Tx(ctx)
+	if err != nil {
+		return nil, err
+	}
+	var (
+		update  bool
+		res     sql.Result
+		builder = sql.Update(card.Table).Where(sql.InInts(card.FieldID, ids...))
+	)
+	if cuo.expired != nil {
+		update = true
+		builder.Set(card.FieldExpired, *cuo.expired)
+		c.Expired = *cuo.expired
+	}
+	if cuo.number != nil {
+		update = true
+		builder.Set(card.FieldNumber, *cuo.number)
+		c.Number = *cuo.number
+	}
+	if update {
+		query, args := builder.Query()
+		if err := tx.Exec(ctx, query, args, &res); err != nil {
+			return nil, rollback(tx, err)
+		}
+	}
+	if cuo.clearedOwner {
+		query, args := sql.Update(card.OwnerTable).
+			SetNull(card.OwnerColumn).
+			Where(sql.InInts(user.FieldID, ids...)).
+			Query()
+		if err := tx.Exec(ctx, query, args, &res); err != nil {
+			return nil, rollback(tx, err)
+		}
+	}
+	if len(cuo.owner) > 0 {
+		for _, id := range ids {
+			eid := keys(cuo.owner)[0]
+			query, args := sql.Update(card.OwnerTable).
+				Set(card.OwnerColumn, eid).
+				Where(sql.EQ(card.FieldID, id).And().IsNull(card.OwnerColumn)).
+				Query()
+			if err := tx.Exec(ctx, query, args, &res); err != nil {
+				return nil, rollback(tx, err)
+			}
+			affected, err := res.RowsAffected()
+			if err != nil {
+				return nil, rollback(tx, err)
+			}
+			if int(affected) < len(cuo.owner) {
+				return nil, rollback(tx, &ErrConstraintFailed{msg: fmt.Sprintf("one of \"owner\" %v already connected to a different \"Card\"", keys(cuo.owner))})
+			}
+		}
+	}
+	if err = tx.Commit(); err != nil {
+		return nil, err
+	}
+	return c, nil
+}

examples/o2o2types/ent/client.go

@@ -0,0 +1,179 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+	"fmt"
+	"log"
+
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/migrate"
+
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/card"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/user"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// Client is the client that holds all ent builders.
+type Client struct {
+	config
+	// Schema is the client for creating, migrating and dropping schema.
+	Schema *migrate.Schema
+	// Card is the client for interacting with the Card builders.
+	Card *CardClient
+	// User is the client for interacting with the User builders.
+	User *UserClient
+}
+
+// NewClient creates a new client configured with the given options.
+func NewClient(opts ...Option) *Client {
+	c := config{log: log.Println}
+	c.options(opts...)
+	return &Client{
+		config: c,
+		Schema: migrate.NewSchema(c.driver),
+		Card:   NewCardClient(c),
+		User:   NewUserClient(c),
+	}
+}
+
+// Tx returns a new transactional client.
+func (c *Client) Tx(ctx context.Context) (*Tx, error) {
+	if _, ok := c.driver.(*txDriver); ok {
+		return nil, fmt.Errorf("ent: cannot start a transaction within a transaction")
+	}
+	tx, err := newTx(ctx, c.driver)
+	if err != nil {
+		return nil, fmt.Errorf("ent: starting a transaction: %v", err)
+	}
+	cfg := config{driver: tx, log: c.log, verbose: c.verbose}
+	return &Tx{
+		config: cfg,
+		Card:   NewCardClient(cfg),
+		User:   NewUserClient(cfg),
+	}, nil
+}
+
+// CardClient is a client for the Card schema.
+type CardClient struct {
+	config
+}
+
+// NewCardClient returns a client for the Card from the given config.
+func NewCardClient(c config) *CardClient {
+	return &CardClient{config: c}
+}
+
+// Create returns a create builder for Card.
+func (c *CardClient) Create() *CardCreate {
+	return &CardCreate{config: c.config}
+}
+
+// Update returns an update builder for Card.
+func (c *CardClient) Update() *CardUpdate {
+	return &CardUpdate{config: c.config}
+}
+
+// UpdateOne returns an update builder for the given entity.
+func (c *CardClient) UpdateOne(ca *Card) *CardUpdateOne {
+	return c.UpdateOneID(ca.ID)
+}
+
+// UpdateOneID returns an update builder for the given id.
+func (c *CardClient) UpdateOneID(id int) *CardUpdateOne {
+	return &CardUpdateOne{config: c.config, id: id}
+}
+
+// Delete returns a delete builder for Card.
+func (c *CardClient) Delete() *CardDelete {
+	return &CardDelete{config: c.config}
+}
+
+// DeleteOne returns a delete builder for the given entity.
+func (c *CardClient) DeleteOne(ca *Card) *CardDeleteOne {
+	return c.DeleteOneID(ca.ID)
+}
+
+// DeleteOneID returns a delete builder for the given id.
+func (c *CardClient) DeleteOneID(id int) *CardDeleteOne {
+	return &CardDeleteOne{c.Delete().Where(card.ID(id))}
+}
+
+// Create returns a query builder for Card.
+func (c *CardClient) Query() *CardQuery {
+	return &CardQuery{config: c.config}
+}
+
+// QueryOwner queries the owner edge of a Card.
+func (c *CardClient) QueryOwner(ca *Card) *UserQuery {
+	query := &UserQuery{config: c.config}
+	id := ca.ID
+	t1 := sql.Table(user.Table)
+	t2 := sql.Select(card.OwnerColumn).
+		From(sql.Table(card.OwnerTable)).
+		Where(sql.EQ(card.FieldID, id))
+	query.sql = sql.Select().From(t1).Join(t2).On(t1.C(user.FieldID), t2.C(card.OwnerColumn))
+
+	return query
+}
+
+// UserClient is a client for the User schema.
+type UserClient struct {
+	config
+}
+
+// NewUserClient returns a client for the User from the given config.
+func NewUserClient(c config) *UserClient {
+	return &UserClient{config: c}
+}
+
+// Create returns a create builder for User.
+func (c *UserClient) Create() *UserCreate {
+	return &UserCreate{config: c.config}
+}
+
+// Update returns an update builder for User.
+func (c *UserClient) Update() *UserUpdate {
+	return &UserUpdate{config: c.config}
+}
+
+// UpdateOne returns an update builder for the given entity.
+func (c *UserClient) UpdateOne(u *User) *UserUpdateOne {
+	return c.UpdateOneID(u.ID)
+}
+
+// UpdateOneID returns an update builder for the given id.
+func (c *UserClient) UpdateOneID(id int) *UserUpdateOne {
+	return &UserUpdateOne{config: c.config, id: id}
+}
+
+// Delete returns a delete builder for User.
+func (c *UserClient) Delete() *UserDelete {
+	return &UserDelete{config: c.config}
+}
+
+// DeleteOne returns a delete builder for the given entity.
+func (c *UserClient) DeleteOne(u *User) *UserDeleteOne {
+	return c.DeleteOneID(u.ID)
+}
+
+// DeleteOneID returns a delete builder for the given id.
+func (c *UserClient) DeleteOneID(id int) *UserDeleteOne {
+	return &UserDeleteOne{c.Delete().Where(user.ID(id))}
+}
+
+// Create returns a query builder for User.
+func (c *UserClient) Query() *UserQuery {
+	return &UserQuery{config: c.config}
+}
+
+// QueryCard queries the card edge of a User.
+func (c *UserClient) QueryCard(u *User) *CardQuery {
+	query := &CardQuery{config: c.config}
+	id := u.ID
+	query.sql = sql.Select().From(sql.Table(card.Table)).
+		Where(sql.EQ(user.CardColumn, id))
+
+	return query
+}

examples/o2o2types/ent/config.go

@@ -0,0 +1,51 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"github.com/facebookincubator/ent/dialect"
+)
+
+// Option function to configure the client.
+type Option func(*config)
+
+// Config is the configuration for the client and its builder.
+type config struct {
+	// driver is the driver used for execute database requests.
+	driver dialect.Driver
+	// verbose enable a verbosity logging.
+	verbose bool
+	// log used for logging on verbose mode.
+	log func(...interface{})
+}
+
+// Options applies the options on the config object.
+func (c *config) options(opts ...Option) {
+	for _, opt := range opts {
+		opt(c)
+	}
+	if c.verbose {
+		c.driver = dialect.Debug(c.driver, c.log)
+	}
+}
+
+// Verbose sets the client logging to verbose.
+func Verbose() Option {
+	return func(c *config) {
+		c.verbose = true
+	}
+}
+
+// Log sets the client logging to verbose.
+func Log(fn func(...interface{})) Option {
+	return func(c *config) {
+		c.log = fn
+	}
+}
+
+// Driver configures the client driver.
+func Driver(driver dialect.Driver) Option {
+	return func(c *config) {
+		c.driver = driver
+	}
+}

examples/o2o2types/ent/context.go

@@ -0,0 +1,20 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+)
+
+type contextKey struct{}
+
+// FromContext returns the Client stored in a context, or nil if there isn't one.
+func FromContext(ctx context.Context) *Client {
+	c, _ := ctx.Value(contextKey{}).(*Client)
+	return c
+}
+
+// NewContext returns a new context with the given Client attached.
+func NewContext(parent context.Context, c *Client) context.Context {
+	return context.WithValue(parent, contextKey{}, c)
+}

examples/o2o2types/ent/ent.go

@@ -0,0 +1,192 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/facebookincubator/ent/dialect"
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// Order applies an ordering on either graph traversal or sql selector.
+type Order func(*sql.Selector)
+
+// Asc applies the given fields in ASC order.
+func Asc(fields ...string) Order {
+	return Order(
+		func(s *sql.Selector) {
+			for _, f := range fields {
+				s.OrderBy(sql.Asc(f))
+			}
+		},
+	)
+}
+
+// Desc applies the given fields in DESC order.
+func Desc(fields ...string) Order {
+	return Order(
+		func(s *sql.Selector) {
+			for _, f := range fields {
+				s.OrderBy(sql.Desc(f))
+			}
+		},
+	)
+}
+
+// Aggregate applies an aggregation step on the group-by traversal/selector.
+type Aggregate struct {
+	// SQL the column wrapped with the aggregation function.
+	SQL func(*sql.Selector) string
+}
+
+// As is a pseudo aggregation function for renaming another other functions with custom names. For example:
+//
+//	GroupBy(field1, field2).
+//	Aggregate(ent.As(ent.Sum(field1), "sum_field1"), (ent.As(ent.Sum(field2), "sum_field2")).
+//	Scan(ctx, &v)
+//
+func As(fn Aggregate, end string) Aggregate {
+	return Aggregate{
+		SQL: func(s *sql.Selector) string {
+			return sql.As(fn.SQL(s), end)
+		},
+	}
+}
+
+// Count applies the "count" aggregation function on each group.
+func Count() Aggregate {
+	return Aggregate{
+		SQL: func(s *sql.Selector) string {
+			return sql.Count("*")
+		},
+	}
+}
+
+// Max applies the "max" aggregation function on the given field of each group.
+func Max(field string) Aggregate {
+	return Aggregate{
+		SQL: func(s *sql.Selector) string {
+			return sql.Max(s.C(field))
+		},
+	}
+}
+
+// Mean applies the "mean" aggregation function on the given field of each group.
+func Mean(field string) Aggregate {
+	return Aggregate{
+		SQL: func(s *sql.Selector) string {
+			return sql.Avg(s.C(field))
+		},
+	}
+}
+
+// Min applies the "min" aggregation function on the given field of each group.
+func Min(field string) Aggregate {
+	return Aggregate{
+		SQL: func(s *sql.Selector) string {
+			return sql.Min(s.C(field))
+		},
+	}
+}
+
+// Sum applies the "sum" aggregation function on the given field of each group.
+func Sum(field string) Aggregate {
+	return Aggregate{
+		SQL: func(s *sql.Selector) string {
+			return sql.Sum(s.C(field))
+		},
+	}
+}
+
+// ErrNotFound returns when trying to fetch a specific entity and it was not found in the database.
+type ErrNotFound struct {
+	label string
+}
+
+// Error implements the error interface.
+func (e *ErrNotFound) Error() string {
+	return fmt.Sprintf("ent: %s not found", e.label)
+}
+
+// IsNotFound returns a boolean indicating whether the error is a not found error.
+func IsNotFound(err error) bool {
+	_, ok := err.(*ErrNotFound)
+	return ok
+}
+
+// MaskNotFound masks nor found error.
+func MaskNotFound(err error) error {
+	if IsNotFound(err) {
+		return nil
+	}
+	return err
+}
+
+// ErrNotSingular returns when trying to fetch a singular entity and more then one was found in the database.
+type ErrNotSingular struct {
+	label string
+}
+
+// Error implements the error interface.
+func (e *ErrNotSingular) Error() string {
+	return fmt.Sprintf("ent: %s not singular", e.label)
+}
+
+// IsNotSingular returns a boolean indicating whether the error is a not singular error.
+func IsNotSingular(err error) bool {
+	_, ok := err.(*ErrNotSingular)
+	return ok
+}
+
+// ErrConstraintFailed returns when trying to create/update one or more entities and
+// one or more of their constraints failed. For example, violation of edge or field uniqueness.
+type ErrConstraintFailed struct {
+	msg  string
+	wrap error
+}
+
+// Error implements the error interface.
+func (e ErrConstraintFailed) Error() string {
+	return fmt.Sprintf("ent: unique constraint failed: %s", e.msg)
+}
+
+// Unwrap implements the errors.Wrapper interface.
+func (e *ErrConstraintFailed) Unwrap() error {
+	return e.wrap
+}
+
+// IsConstraintFailure returns a boolean indicating whether the error is a constraint failure.
+func IsConstraintFailure(err error) bool {
+	_, ok := err.(*ErrConstraintFailed)
+	return ok
+}
+
+func isSQLConstraintError(err error) (*ErrConstraintFailed, bool) {
+	// Error number 1062 is ER_DUP_ENTRY in mysql, and "UNIQUE constraint failed" is SQLite prefix.
+	if msg := err.Error(); strings.HasPrefix(msg, "Error 1062") || strings.HasPrefix(msg, "UNIQUE constraint failed") {
+		return &ErrConstraintFailed{msg, err}, true
+	}
+	return nil, false
+}
+
+// rollback calls to tx.Rollback and wraps the given error with the rollback error if occurred.
+func rollback(tx dialect.Tx, err error) error {
+	if rerr := tx.Rollback(); rerr != nil {
+		err = fmt.Errorf("%s: %v", err.Error(), rerr)
+	}
+	if err, ok := isSQLConstraintError(err); ok {
+		return err
+	}
+	return err
+}
+
+// keys returns the keys/ids from the edge map.
+func keys(m map[int]struct{}) []int {
+	s := make([]int, 0, len(m))
+	for id, _ := range m {
+		s = append(s, id)
+	}
+	return s
+}

examples/o2o2types/ent/example_test.go

@@ -0,0 +1,80 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+	"log"
+	"time"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// dsn for the database. In order to run the tests locally, run the following command:
+//
+//	 ENT_INTEGRATION_ENDPOINT="root:pass@tcp(localhost:3306)/test?parseTime=True" go test -v
+//
+var dsn string
+
+func ExampleCard() {
+	if dsn == "" {
+		return
+	}
+	ctx := context.Background()
+	drv, err := sql.Open("mysql", dsn)
+	if err != nil {
+		log.Fatalf("failed creating database client: %v", err)
+	}
+	defer drv.Close()
+	client := NewClient(Driver(drv))
+	// creating vertices for the card's edges.
+
+	// create card vertex with its edges.
+	c := client.Card.
+		Create().
+		SetExpired(time.Now()).
+		SetNumber("string").
+		SaveX(ctx)
+	log.Println("card created:", c)
+
+	// query edges.
+
+	// Output:
+}
+func ExampleUser() {
+	if dsn == "" {
+		return
+	}
+	ctx := context.Background()
+	drv, err := sql.Open("mysql", dsn)
+	if err != nil {
+		log.Fatalf("failed creating database client: %v", err)
+	}
+	defer drv.Close()
+	client := NewClient(Driver(drv))
+	// creating vertices for the user's edges.
+	c0 := client.Card.
+		Create().
+		SetExpired(time.Now()).
+		SetNumber("string").
+		SaveX(ctx)
+	log.Println("card created:", c0)
+
+	// create user vertex with its edges.
+	u := client.User.
+		Create().
+		SetAge(1).
+		SetName("string").
+		SetCard(c0).
+		SaveX(ctx)
+	log.Println("user created:", u)
+
+	// query edges.
+	c0, err = u.QueryCard().First(ctx)
+	if err != nil {
+		log.Fatalf("failed querying card: %v", err)
+	}
+	log.Println("card found:", c0)
+
+	// Output:
+}

examples/o2o2types/ent/generate.go

@@ -0,0 +1,3 @@
+package ent
+
+//go:generate go run ../../../entc/cmd/entc/entc.go generate --header "Code generated (@generated) by entc, DO NOT EDIT." ./schema

examples/o2o2types/ent/migrate/migrate.go

@@ -0,0 +1,48 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package migrate
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/facebookincubator/ent/dialect"
+	"github.com/facebookincubator/ent/dialect/sql/schema"
+)
+
+var (
+	// WithGlobalUniqueID sets the universal ids options to the migration.
+	// If this option is enabled, ent migration will allocate a 1<<32 range
+	// for the ids of each entity (table).
+	// Note that this option cannot be applied on tables that already exist.
+	WithGlobalUniqueID = schema.WithGlobalUniqueID
+	// WithDropColumn sets the drop column option to the migration.
+	// If this option is enabled, ent migration will drop old columns
+	// that were used for both fields and edges. This defaults to false.
+	WithDropColumn = schema.WithDropColumn
+	// WithDropIndex sets the drop index option to the migration.
+	// If this option is enabled, ent migration will drop old indexes
+	// that were defined in the schema. This defaults to false.
+	// Note that unique constraints are defined using `UNIQUE INDEX`,
+	// and therefore, it's recommended to enable this option to get more
+	// flexibility in the schema changes.
+	WithDropIndex = schema.WithDropIndex
+)
+
+// Schema is the API for creating, migrating and dropping a schema.
+type Schema struct {
+	drv         dialect.Driver
+	universalID bool
+}
+
+// NewSchema creates a new schema client.
+func NewSchema(drv dialect.Driver) *Schema { return &Schema{drv: drv} }
+
+// Create creates all schema resources.
+func (s *Schema) Create(ctx context.Context, opts ...schema.MigrateOption) error {
+	migrate, err := schema.NewMigrate(s.drv, opts...)
+	if err != nil {
+		return fmt.Errorf("ent/migrate: %v", err)
+	}
+	return migrate.Create(ctx, Tables...)
+}

examples/o2o2types/ent/migrate/schema.go

@@ -0,0 +1,55 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package migrate
+
+import (
+	"github.com/facebookincubator/ent/dialect/sql/schema"
+	"github.com/facebookincubator/ent/schema/field"
+)
+
+var (
+	// CardsColumns holds the columns for the "cards" table.
+	CardsColumns = []*schema.Column{
+		{Name: "id", Type: field.TypeInt, Increment: true},
+		{Name: "expired", Type: field.TypeTime},
+		{Name: "number", Type: field.TypeString},
+		{Name: "owner_id", Type: field.TypeInt, Unique: true, Nullable: true},
+	}
+	// CardsTable holds the schema information for the "cards" table.
+	CardsTable = &schema.Table{
+		Name:       "cards",
+		Columns:    CardsColumns,
+		PrimaryKey: []*schema.Column{CardsColumns[0]},
+		ForeignKeys: []*schema.ForeignKey{
+			{
+				Symbol:  "cards_users_card",
+				Columns: []*schema.Column{CardsColumns[3]},
+
+				RefColumns: []*schema.Column{UsersColumns[0]},
+				OnDelete:   schema.SetNull,
+			},
+		},
+	}
+	// UsersColumns holds the columns for the "users" table.
+	UsersColumns = []*schema.Column{
+		{Name: "id", Type: field.TypeInt, Increment: true},
+		{Name: "age", Type: field.TypeInt},
+		{Name: "name", Type: field.TypeString},
+	}
+	// UsersTable holds the schema information for the "users" table.
+	UsersTable = &schema.Table{
+		Name:        "users",
+		Columns:     UsersColumns,
+		PrimaryKey:  []*schema.Column{UsersColumns[0]},
+		ForeignKeys: []*schema.ForeignKey{},
+	}
+	// Tables holds all the tables in the schema.
+	Tables = []*schema.Table{
+		CardsTable,
+		UsersTable,
+	}
+)
+
+func init() {
+	CardsTable.ForeignKeys[0].RefTable = UsersTable
+}

examples/o2o2types/ent/predicate/predicate.go

@@ -0,0 +1,13 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package predicate
+
+import (
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// Card is the predicate function for card builders.
+type Card func(*sql.Selector)
+
+// User is the predicate function for user builders.
+type User func(*sql.Selector)

examples/o2o2types/ent/schema/card.go

@@ -0,0 +1,33 @@
+package schema
+
+import (
+	"github.com/facebookincubator/ent"
+	"github.com/facebookincubator/ent/schema/edge"
+	"github.com/facebookincubator/ent/schema/field"
+)
+
+// Card holds the schema definition for the Card entity.
+type Card struct {
+	ent.Schema
+}
+
+// Fields of the Card.
+func (Card) Fields() []ent.Field {
+	return []ent.Field{
+		field.Time("expired"),
+		field.String("number"),
+	}
+}
+
+// Edges of the Card.
+func (Card) Edges() []ent.Edge {
+	return []ent.Edge{
+		edge.From("owner", User.Type).
+			Ref("card").
+			Unique().
+			// We add the "Required" method to the builder
+			// to make this edge required on entity creation.
+			// i.e. Card cannot be created without its owner.
+			Required(),
+	}
+}

examples/o2o2types/ent/schema/user.go

@@ -0,0 +1,28 @@
+package schema
+
+import (
+	"github.com/facebookincubator/ent"
+	"github.com/facebookincubator/ent/schema/edge"
+	"github.com/facebookincubator/ent/schema/field"
+)
+
+// User holds the schema definition for the User entity.
+type User struct {
+	ent.Schema
+}
+
+// Fields of the User.
+func (User) Fields() []ent.Field {
+	return []ent.Field{
+		field.Int("age"),
+		field.String("name"),
+	}
+}
+
+// Edges of the User.
+func (User) Edges() []ent.Edge {
+	return []ent.Edge{
+		edge.To("card", Card.Type).
+			Unique(),
+	}
+}

examples/o2o2types/ent/tx.go

@@ -0,0 +1,96 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+
+	"github.com/facebookincubator/ent/dialect"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/migrate"
+)
+
+// Tx is a transactional client that is created by calling Client.Tx().
+type Tx struct {
+	config
+	// Card is the client for interacting with the Card builders.
+	Card *CardClient
+	// User is the client for interacting with the User builders.
+	User *UserClient
+}
+
+// Commit commits the transaction.
+func (tx *Tx) Commit() error {
+	return tx.config.driver.(*txDriver).tx.Commit()
+}
+
+// Rollback rollbacks the transaction.
+func (tx *Tx) Rollback() error {
+	return tx.config.driver.(*txDriver).tx.Rollback()
+}
+
+// Client returns a Client that binds to current transaction.
+func (tx *Tx) Client() *Client {
+	return &Client{
+		config: tx.config,
+		Schema: migrate.NewSchema(tx.driver),
+		Card:   NewCardClient(tx.config),
+		User:   NewUserClient(tx.config),
+	}
+}
+
+// txDriver wraps the given dialect.Tx with a nop dialect.Driver implementation.
+// The idea is to support transactions without adding any extra code to the builders.
+// When a builder calls to driver.Tx(), it gets the same dialect.Tx instance.
+// Commit and Rollback are nop for the internal builders and the user must call one
+// of them in order to commit or rollback the transaction.
+//
+// If a closed transaction is embedded in one of the generated entities, and the entity
+// applies a query, for example: Card.QueryXXX(), the query will be executed
+// through the driver which created this transaction.
+//
+// Note that txDriver is not goroutine safe.
+type txDriver struct {
+	// the driver we started the transaction from.
+	drv dialect.Driver
+	// tx is the underlying transaction.
+	tx dialect.Tx
+}
+
+// newTx creates a new transactional driver.
+func newTx(ctx context.Context, drv dialect.Driver) (*txDriver, error) {
+	tx, err := drv.Tx(ctx)
+	if err != nil {
+		return nil, err
+	}
+	return &txDriver{tx: tx, drv: drv}, nil
+}
+
+// Tx returns the transaction wrapper (txDriver) to avoid Commit or Rollback calls
+// from the internal builders. Should be called only by the internal builders.
+func (tx *txDriver) Tx(context.Context) (dialect.Tx, error) { return tx, nil }
+
+// Dialect returns the dialect of the driver we started the transaction from.
+func (tx *txDriver) Dialect() string { return tx.drv.Dialect() }
+
+// Close is a nop close.
+func (*txDriver) Close() error { return nil }
+
+// Commit is a nop commit for the internal builders.
+// User must call `Tx.Commit` in order to commit the transaction.
+func (*txDriver) Commit() error { return nil }
+
+// Rollback is a nop rollback for the internal builders.
+// User must call `Tx.Rollback` in order to rollback the transaction.
+func (*txDriver) Rollback() error { return nil }
+
+// Exec calls tx.Exec.
+func (tx *txDriver) Exec(ctx context.Context, query string, args, v interface{}) error {
+	return tx.tx.Exec(ctx, query, args, v)
+}
+
+// Query calls tx.Query.
+func (tx *txDriver) Query(ctx context.Context, query string, args, v interface{}) error {
+	return tx.tx.Query(ctx, query, args, v)
+}
+
+var _ dialect.Driver = (*txDriver)(nil)

examples/o2o2types/ent/user.go

@@ -0,0 +1,97 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// User is the model entity for the User schema.
+type User struct {
+	config
+	// ID of the ent.
+	ID int `json:"id,omitempty"`
+	// Age holds the value of the "age" field.
+	Age int `json:"age,omitempty"`
+	// Name holds the value of the "name" field.
+	Name string `json:"name,omitempty"`
+}
+
+// FromRows scans the sql response data into User.
+func (u *User) FromRows(rows *sql.Rows) error {
+	var vu struct {
+		ID   int
+		Age  sql.NullInt64
+		Name sql.NullString
+	}
+	// the order here should be the same as in the `user.Columns`.
+	if err := rows.Scan(
+		&vu.ID,
+		&vu.Age,
+		&vu.Name,
+	); err != nil {
+		return err
+	}
+	u.ID = vu.ID
+	u.Age = int(vu.Age.Int64)
+	u.Name = vu.Name.String
+	return nil
+}
+
+// QueryCard queries the card edge of the User.
+func (u *User) QueryCard() *CardQuery {
+	return (&UserClient{u.config}).QueryCard(u)
+}
+
+// Update returns a builder for updating this User.
+// Note that, you need to call User.Unwrap() before calling this method, if this User
+// was returned from a transaction, and the transaction was committed or rolled back.
+func (u *User) Update() *UserUpdateOne {
+	return (&UserClient{u.config}).UpdateOne(u)
+}
+
+// Unwrap unwraps the entity that was returned from a transaction after it was closed,
+// so that all next queries will be executed through the driver which created the transaction.
+func (u *User) Unwrap() *User {
+	tx, ok := u.config.driver.(*txDriver)
+	if !ok {
+		panic("ent: User is not a transactional entity")
+	}
+	u.config.driver = tx.drv
+	return u
+}
+
+// String implements the fmt.Stringer.
+func (u *User) String() string {
+	buf := bytes.NewBuffer(nil)
+	buf.WriteString("User(")
+	buf.WriteString(fmt.Sprintf("id=%v", u.ID))
+	buf.WriteString(fmt.Sprintf(", age=%v", u.Age))
+	buf.WriteString(fmt.Sprintf(", name=%v", u.Name))
+	buf.WriteString(")")
+	return buf.String()
+}
+
+// Users is a parsable slice of User.
+type Users []*User
+
+// FromRows scans the sql response data into Users.
+func (u *Users) FromRows(rows *sql.Rows) error {
+	for rows.Next() {
+		vu := &User{}
+		if err := vu.FromRows(rows); err != nil {
+			return err
+		}
+		*u = append(*u, vu)
+	}
+	return nil
+}
+
+func (u Users) config(cfg config) {
+	for i := range u {
+		u[i].config = cfg
+	}
+}

examples/o2o2types/ent/user/user.go

@@ -0,0 +1,31 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package user
+
+const (
+	// Label holds the string label denoting the user type in the database.
+	Label = "user"
+	// FieldID holds the string denoting the id field in the database.
+	FieldID = "id"
+	// FieldAge holds the string denoting the age vertex property in the database.
+	FieldAge = "age"
+	// FieldName holds the string denoting the name vertex property in the database.
+	FieldName = "name"
+
+	// Table holds the table name of the user in the database.
+	Table = "users"
+	// CardTable is the table the holds the card relation/edge.
+	CardTable = "cards"
+	// CardInverseTable is the table name for the Card entity.
+	// It exists in this package in order to avoid circular dependency with the "card" package.
+	CardInverseTable = "cards"
+	// CardColumn is the table column denoting the card relation/edge.
+	CardColumn = "owner_id"
+)
+
+// Columns holds all SQL columns are user fields.
+var Columns = []string{
+	FieldID,
+	FieldAge,
+	FieldName,
+}

examples/o2o2types/ent/user/where.go

@@ -0,0 +1,413 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package user
+
+import (
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/predicate"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// ID filters vertices based on their identifier.
+func ID(id int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.EQ(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDEQ applies the EQ predicate on the ID field.
+func IDEQ(id int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.EQ(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDNEQ applies the NEQ predicate on the ID field.
+func IDNEQ(id int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.NEQ(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDGT applies the GT predicate on the ID field.
+func IDGT(id int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.GT(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDGTE applies the GTE predicate on the ID field.
+func IDGTE(id int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.GTE(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDLT applies the LT predicate on the ID field.
+func IDLT(id int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.LT(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDLTE applies the LTE predicate on the ID field.
+func IDLTE(id int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.LTE(s.C(FieldID), id))
+		},
+	)
+}
+
+// IDIn applies the In predicate on the ID field.
+func IDIn(ids ...int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			// if not arguments were provided, append the FALSE constants,
+			// since we can't apply "IN ()". This will make this predicate falsy.
+			if len(ids) == 0 {
+				s.Where(sql.False())
+				return
+			}
+			v := make([]interface{}, len(ids))
+			for i := range v {
+				v[i] = ids[i]
+			}
+			s.Where(sql.In(s.C(FieldID), v...))
+		},
+	)
+}
+
+// IDNotIn applies the NotIn predicate on the ID field.
+func IDNotIn(ids ...int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			// if not arguments were provided, append the FALSE constants,
+			// since we can't apply "IN ()". This will make this predicate falsy.
+			if len(ids) == 0 {
+				s.Where(sql.False())
+				return
+			}
+			v := make([]interface{}, len(ids))
+			for i := range v {
+				v[i] = ids[i]
+			}
+			s.Where(sql.NotIn(s.C(FieldID), v...))
+		},
+	)
+}
+
+// Age applies equality check predicate on the "age" field. It's identical to AgeEQ.
+func Age(v int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.EQ(s.C(FieldAge), v))
+		},
+	)
+}
+
+// Name applies equality check predicate on the "name" field. It's identical to NameEQ.
+func Name(v string) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.EQ(s.C(FieldName), v))
+		},
+	)
+}
+
+// AgeEQ applies the EQ predicate on the "age" field.
+func AgeEQ(v int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.EQ(s.C(FieldAge), v))
+		},
+	)
+}
+
+// AgeNEQ applies the NEQ predicate on the "age" field.
+func AgeNEQ(v int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.NEQ(s.C(FieldAge), v))
+		},
+	)
+}
+
+// AgeGT applies the GT predicate on the "age" field.
+func AgeGT(v int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.GT(s.C(FieldAge), v))
+		},
+	)
+}
+
+// AgeGTE applies the GTE predicate on the "age" field.
+func AgeGTE(v int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.GTE(s.C(FieldAge), v))
+		},
+	)
+}
+
+// AgeLT applies the LT predicate on the "age" field.
+func AgeLT(v int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.LT(s.C(FieldAge), v))
+		},
+	)
+}
+
+// AgeLTE applies the LTE predicate on the "age" field.
+func AgeLTE(v int) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.LTE(s.C(FieldAge), v))
+		},
+	)
+}
+
+// AgeIn applies the In predicate on the "age" field.
+func AgeIn(vs ...int) predicate.User {
+	v := make([]interface{}, len(vs))
+	for i := range v {
+		v[i] = vs[i]
+	}
+	return predicate.User(
+		func(s *sql.Selector) {
+			// if not arguments were provided, append the FALSE constants,
+			// since we can't apply "IN ()". This will make this predicate falsy.
+			if len(vs) == 0 {
+				s.Where(sql.False())
+				return
+			}
+			s.Where(sql.In(s.C(FieldAge), v...))
+		},
+	)
+}
+
+// AgeNotIn applies the NotIn predicate on the "age" field.
+func AgeNotIn(vs ...int) predicate.User {
+	v := make([]interface{}, len(vs))
+	for i := range v {
+		v[i] = vs[i]
+	}
+	return predicate.User(
+		func(s *sql.Selector) {
+			// if not arguments were provided, append the FALSE constants,
+			// since we can't apply "IN ()". This will make this predicate falsy.
+			if len(vs) == 0 {
+				s.Where(sql.False())
+				return
+			}
+			s.Where(sql.NotIn(s.C(FieldAge), v...))
+		},
+	)
+}
+
+// NameEQ applies the EQ predicate on the "name" field.
+func NameEQ(v string) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.EQ(s.C(FieldName), v))
+		},
+	)
+}
+
+// NameNEQ applies the NEQ predicate on the "name" field.
+func NameNEQ(v string) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.NEQ(s.C(FieldName), v))
+		},
+	)
+}
+
+// NameGT applies the GT predicate on the "name" field.
+func NameGT(v string) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.GT(s.C(FieldName), v))
+		},
+	)
+}
+
+// NameGTE applies the GTE predicate on the "name" field.
+func NameGTE(v string) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.GTE(s.C(FieldName), v))
+		},
+	)
+}
+
+// NameLT applies the LT predicate on the "name" field.
+func NameLT(v string) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.LT(s.C(FieldName), v))
+		},
+	)
+}
+
+// NameLTE applies the LTE predicate on the "name" field.
+func NameLTE(v string) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.LTE(s.C(FieldName), v))
+		},
+	)
+}
+
+// NameIn applies the In predicate on the "name" field.
+func NameIn(vs ...string) predicate.User {
+	v := make([]interface{}, len(vs))
+	for i := range v {
+		v[i] = vs[i]
+	}
+	return predicate.User(
+		func(s *sql.Selector) {
+			// if not arguments were provided, append the FALSE constants,
+			// since we can't apply "IN ()". This will make this predicate falsy.
+			if len(vs) == 0 {
+				s.Where(sql.False())
+				return
+			}
+			s.Where(sql.In(s.C(FieldName), v...))
+		},
+	)
+}
+
+// NameNotIn applies the NotIn predicate on the "name" field.
+func NameNotIn(vs ...string) predicate.User {
+	v := make([]interface{}, len(vs))
+	for i := range v {
+		v[i] = vs[i]
+	}
+	return predicate.User(
+		func(s *sql.Selector) {
+			// if not arguments were provided, append the FALSE constants,
+			// since we can't apply "IN ()". This will make this predicate falsy.
+			if len(vs) == 0 {
+				s.Where(sql.False())
+				return
+			}
+			s.Where(sql.NotIn(s.C(FieldName), v...))
+		},
+	)
+}
+
+// NameContains applies the Contains predicate on the "name" field.
+func NameContains(v string) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.Contains(s.C(FieldName), v))
+		},
+	)
+}
+
+// NameHasPrefix applies the HasPrefix predicate on the "name" field.
+func NameHasPrefix(v string) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.HasPrefix(s.C(FieldName), v))
+		},
+	)
+}
+
+// NameHasSuffix applies the HasSuffix predicate on the "name" field.
+func NameHasSuffix(v string) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.HasSuffix(s.C(FieldName), v))
+		},
+	)
+}
+
+// NameContainsFold applies the ContainsFold predicate on the "name" field.
+func NameContainsFold(v string) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			s.Where(sql.ContainsFold(s.C(FieldName), v))
+		},
+	)
+}
+
+// HasCard applies the HasEdge predicate on the "card" edge.
+func HasCard() predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			t1 := s.Table()
+			s.Where(
+				sql.In(
+					t1.C(FieldID),
+					sql.Select(CardColumn).
+						From(sql.Table(CardTable)).
+						Where(sql.NotNull(CardColumn)),
+				),
+			)
+		},
+	)
+}
+
+// HasCardWith applies the HasEdge predicate on the "card" edge with a given conditions (other predicates).
+func HasCardWith(preds ...predicate.Card) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			t1 := s.Table()
+			t2 := sql.Select(CardColumn).From(sql.Table(CardTable))
+			for _, p := range preds {
+				p(t2)
+			}
+			s.Where(sql.In(t1.C(FieldID), t2))
+		},
+	)
+}
+
+// And groups list of predicates with the AND operator between them.
+func And(predicates ...predicate.User) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			for _, p := range predicates {
+				p(s)
+			}
+		},
+	)
+}
+
+// Or groups list of predicates with the OR operator between them.
+func Or(predicates ...predicate.User) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			for i, p := range predicates {
+				if i > 0 {
+					s.Or()
+				}
+				p(s)
+			}
+		},
+	)
+}
+
+// Not applies the not operator on the given predicate.
+func Not(p predicate.User) predicate.User {
+	return predicate.User(
+		func(s *sql.Selector) {
+			p(s.Not())
+		},
+	)
+}

examples/o2o2types/ent/user_create.go

@@ -0,0 +1,129 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/card"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/user"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// UserCreate is the builder for creating a User entity.
+type UserCreate struct {
+	config
+	age  *int
+	name *string
+	card map[int]struct{}
+}
+
+// SetAge sets the age field.
+func (uc *UserCreate) SetAge(i int) *UserCreate {
+	uc.age = &i
+	return uc
+}
+
+// SetName sets the name field.
+func (uc *UserCreate) SetName(s string) *UserCreate {
+	uc.name = &s
+	return uc
+}
+
+// SetCardID sets the card edge to Card by id.
+func (uc *UserCreate) SetCardID(id int) *UserCreate {
+	if uc.card == nil {
+		uc.card = make(map[int]struct{})
+	}
+	uc.card[id] = struct{}{}
+	return uc
+}
+
+// SetNillableCardID sets the card edge to Card by id if the given value is not nil.
+func (uc *UserCreate) SetNillableCardID(id *int) *UserCreate {
+	if id != nil {
+		uc = uc.SetCardID(*id)
+	}
+	return uc
+}
+
+// SetCard sets the card edge to Card.
+func (uc *UserCreate) SetCard(c *Card) *UserCreate {
+	return uc.SetCardID(c.ID)
+}
+
+// Save creates the User in the database.
+func (uc *UserCreate) Save(ctx context.Context) (*User, error) {
+	if uc.age == nil {
+		return nil, errors.New("ent: missing required field \"age\"")
+	}
+	if uc.name == nil {
+		return nil, errors.New("ent: missing required field \"name\"")
+	}
+	if len(uc.card) > 1 {
+		return nil, errors.New("ent: multiple assignments on a unique edge \"card\"")
+	}
+	return uc.sqlSave(ctx)
+}
+
+// SaveX calls Save and panics if Save returns an error.
+func (uc *UserCreate) SaveX(ctx context.Context) *User {
+	v, err := uc.Save(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+func (uc *UserCreate) sqlSave(ctx context.Context) (*User, error) {
+	var (
+		res sql.Result
+		u   = &User{config: uc.config}
+	)
+	tx, err := uc.driver.Tx(ctx)
+	if err != nil {
+		return nil, err
+	}
+	builder := sql.Insert(user.Table).Default(uc.driver.Dialect())
+	if uc.age != nil {
+		builder.Set(user.FieldAge, *uc.age)
+		u.Age = *uc.age
+	}
+	if uc.name != nil {
+		builder.Set(user.FieldName, *uc.name)
+		u.Name = *uc.name
+	}
+	query, args := builder.Query()
+	if err := tx.Exec(ctx, query, args, &res); err != nil {
+		return nil, rollback(tx, err)
+	}
+	id, err := res.LastInsertId()
+	if err != nil {
+		return nil, rollback(tx, err)
+	}
+	u.ID = int(id)
+	if len(uc.card) > 0 {
+		eid := keys(uc.card)[0]
+		query, args := sql.Update(user.CardTable).
+			Set(user.CardColumn, id).
+			Where(sql.EQ(card.FieldID, eid).And().IsNull(user.CardColumn)).
+			Query()
+		if err := tx.Exec(ctx, query, args, &res); err != nil {
+			return nil, rollback(tx, err)
+		}
+		affected, err := res.RowsAffected()
+		if err != nil {
+			return nil, rollback(tx, err)
+		}
+		if int(affected) < len(uc.card) {
+			return nil, rollback(tx, &ErrConstraintFailed{msg: fmt.Sprintf("one of \"card\" %v already connected to a different \"User\"", keys(uc.card))})
+		}
+	}
+	if err := tx.Commit(); err != nil {
+		return nil, err
+	}
+	return u, nil
+}

examples/o2o2types/ent/user_delete.go

@@ -0,0 +1,61 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/predicate"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/user"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// UserDelete is the builder for deleting a User entity.
+type UserDelete struct {
+	config
+	predicates []predicate.User
+}
+
+// Where adds a new predicate for the builder.
+func (ud *UserDelete) Where(ps ...predicate.User) *UserDelete {
+	ud.predicates = append(ud.predicates, ps...)
+	return ud
+}
+
+// Exec executes the deletion query.
+func (ud *UserDelete) Exec(ctx context.Context) error {
+	return ud.sqlExec(ctx)
+}
+
+// ExecX is like Exec, but panics if an error occurs.
+func (ud *UserDelete) ExecX(ctx context.Context) {
+	if err := ud.Exec(ctx); err != nil {
+		panic(err)
+	}
+}
+
+func (ud *UserDelete) sqlExec(ctx context.Context) error {
+	var res sql.Result
+	selector := sql.Select().From(sql.Table(user.Table))
+	for _, p := range ud.predicates {
+		p(selector)
+	}
+	query, args := sql.Delete(user.Table).FromSelect(selector).Query()
+	return ud.driver.Exec(ctx, query, args, &res)
+}
+
+// UserDeleteOne is the builder for deleting a single User entity.
+type UserDeleteOne struct {
+	ud *UserDelete
+}
+
+// Exec executes the deletion query.
+func (udo *UserDeleteOne) Exec(ctx context.Context) error {
+	return udo.ud.Exec(ctx)
+}
+
+// ExecX is like Exec, but panics if an error occurs.
+func (udo *UserDeleteOne) ExecX(ctx context.Context) {
+	udo.ud.ExecX(ctx)
+}

examples/o2o2types/ent/user_query.go

@@ -0,0 +1,483 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"math"
+
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/card"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/predicate"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/user"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// UserQuery is the builder for querying User entities.
+type UserQuery struct {
+	config
+	limit      *int
+	offset     *int
+	order      []Order
+	unique     []string
+	predicates []predicate.User
+	// intermediate queries.
+	sql *sql.Selector
+}
+
+// Where adds a new predicate for the builder.
+func (uq *UserQuery) Where(ps ...predicate.User) *UserQuery {
+	uq.predicates = append(uq.predicates, ps...)
+	return uq
+}
+
+// Limit adds a limit step to the query.
+func (uq *UserQuery) Limit(limit int) *UserQuery {
+	uq.limit = &limit
+	return uq
+}
+
+// Offset adds an offset step to the query.
+func (uq *UserQuery) Offset(offset int) *UserQuery {
+	uq.offset = &offset
+	return uq
+}
+
+// Order adds an order step to the query.
+func (uq *UserQuery) Order(o ...Order) *UserQuery {
+	uq.order = append(uq.order, o...)
+	return uq
+}
+
+// QueryCard chains the current query on the card edge.
+func (uq *UserQuery) QueryCard() *CardQuery {
+	query := &CardQuery{config: uq.config}
+	t1 := sql.Table(card.Table)
+	t2 := uq.sqlQuery()
+	t2.Select(t2.C(user.FieldID))
+	query.sql = sql.Select().
+		From(t1).
+		Join(t2).
+		On(t1.C(user.CardColumn), t2.C(user.FieldID))
+	return query
+}
+
+// Get returns a User entity by its id.
+func (uq *UserQuery) Get(ctx context.Context, id int) (*User, error) {
+	return uq.Where(user.ID(id)).Only(ctx)
+}
+
+// GetX is like Get, but panics if an error occurs.
+func (uq *UserQuery) GetX(ctx context.Context, id int) *User {
+	u, err := uq.Get(ctx, id)
+	if err != nil {
+		panic(err)
+	}
+	return u
+}
+
+// First returns the first User entity in the query. Returns *ErrNotFound when no user was found.
+func (uq *UserQuery) First(ctx context.Context) (*User, error) {
+	us, err := uq.Limit(1).All(ctx)
+	if err != nil {
+		return nil, err
+	}
+	if len(us) == 0 {
+		return nil, &ErrNotFound{user.Label}
+	}
+	return us[0], nil
+}
+
+// FirstX is like First, but panics if an error occurs.
+func (uq *UserQuery) FirstX(ctx context.Context) *User {
+	u, err := uq.First(ctx)
+	if err != nil && !IsNotFound(err) {
+		panic(err)
+	}
+	return u
+}
+
+// FirstID returns the first User id in the query. Returns *ErrNotFound when no id was found.
+func (uq *UserQuery) FirstID(ctx context.Context) (id int, err error) {
+	var ids []int
+	if ids, err = uq.Limit(1).IDs(ctx); err != nil {
+		return
+	}
+	if len(ids) == 0 {
+		err = &ErrNotFound{user.Label}
+		return
+	}
+	return ids[0], nil
+}
+
+// FirstXID is like FirstID, but panics if an error occurs.
+func (uq *UserQuery) FirstXID(ctx context.Context) int {
+	id, err := uq.FirstID(ctx)
+	if err != nil && !IsNotFound(err) {
+		panic(err)
+	}
+	return id
+}
+
+// Only returns the only User entity in the query, returns an error if not exactly one entity was returned.
+func (uq *UserQuery) Only(ctx context.Context) (*User, error) {
+	us, err := uq.Limit(2).All(ctx)
+	if err != nil {
+		return nil, err
+	}
+	switch len(us) {
+	case 1:
+		return us[0], nil
+	case 0:
+		return nil, &ErrNotFound{user.Label}
+	default:
+		return nil, &ErrNotSingular{user.Label}
+	}
+}
+
+// OnlyX is like Only, but panics if an error occurs.
+func (uq *UserQuery) OnlyX(ctx context.Context) *User {
+	u, err := uq.Only(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return u
+}
+
+// OnlyID returns the only User id in the query, returns an error if not exactly one id was returned.
+func (uq *UserQuery) OnlyID(ctx context.Context) (id int, err error) {
+	var ids []int
+	if ids, err = uq.Limit(2).IDs(ctx); err != nil {
+		return
+	}
+	switch len(ids) {
+	case 1:
+		id = ids[0]
+	case 0:
+		err = &ErrNotFound{user.Label}
+	default:
+		err = &ErrNotSingular{user.Label}
+	}
+	return
+}
+
+// OnlyXID is like OnlyID, but panics if an error occurs.
+func (uq *UserQuery) OnlyXID(ctx context.Context) int {
+	id, err := uq.OnlyID(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return id
+}
+
+// All executes the query and returns a list of Users.
+func (uq *UserQuery) All(ctx context.Context) ([]*User, error) {
+	return uq.sqlAll(ctx)
+}
+
+// AllX is like All, but panics if an error occurs.
+func (uq *UserQuery) AllX(ctx context.Context) []*User {
+	us, err := uq.All(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return us
+}
+
+// IDs executes the query and returns a list of User ids.
+func (uq *UserQuery) IDs(ctx context.Context) ([]int, error) {
+	return uq.sqlIDs(ctx)
+}
+
+// IDsX is like IDs, but panics if an error occurs.
+func (uq *UserQuery) IDsX(ctx context.Context) []int {
+	ids, err := uq.IDs(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return ids
+}
+
+// Count returns the count of the given query.
+func (uq *UserQuery) Count(ctx context.Context) (int, error) {
+	return uq.sqlCount(ctx)
+}
+
+// CountX is like Count, but panics if an error occurs.
+func (uq *UserQuery) CountX(ctx context.Context) int {
+	count, err := uq.Count(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return count
+}
+
+// Exist returns true if the query has elements in the graph.
+func (uq *UserQuery) Exist(ctx context.Context) (bool, error) {
+	return uq.sqlExist(ctx)
+}
+
+// ExistX is like Exist, but panics if an error occurs.
+func (uq *UserQuery) ExistX(ctx context.Context) bool {
+	exist, err := uq.Exist(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return exist
+}
+
+// Clone returns a duplicate of the query builder, including all associated steps. It can be
+// used to prepare common query builders and use them differently after the clone is made.
+func (uq *UserQuery) Clone() *UserQuery {
+	return &UserQuery{
+		config:     uq.config,
+		limit:      uq.limit,
+		offset:     uq.offset,
+		order:      append([]Order{}, uq.order...),
+		unique:     append([]string{}, uq.unique...),
+		predicates: append([]predicate.User{}, uq.predicates...),
+		// clone intermediate queries.
+		sql: uq.sql.Clone(),
+	}
+}
+
+// GroupBy used to group vertices by one or more fields/columns.
+// It is often used with aggregate functions, like: count, max, mean, min, sum.
+//
+// Example:
+//
+//	var v []struct {
+//		Age int `json:"age,omitempty"`
+//		Count int `json:"count,omitempty"`
+//	}
+//
+//	client.User.Query().
+//		GroupBy(user.FieldAge).
+//		Aggregate(ent.Count()).
+//		Scan(ctx, &v)
+//
+func (uq *UserQuery) GroupBy(field string, fields ...string) *UserGroupBy {
+	group := &UserGroupBy{config: uq.config}
+	group.fields = append([]string{field}, fields...)
+	group.sql = uq.sqlQuery()
+	return group
+}
+
+func (uq *UserQuery) sqlAll(ctx context.Context) ([]*User, error) {
+	rows := &sql.Rows{}
+	selector := uq.sqlQuery()
+	if unique := uq.unique; len(unique) == 0 {
+		selector.Distinct()
+	}
+	query, args := selector.Query()
+	if err := uq.driver.Query(ctx, query, args, rows); err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var us Users
+	if err := us.FromRows(rows); err != nil {
+		return nil, err
+	}
+	us.config(uq.config)
+	return us, nil
+}
+
+func (uq *UserQuery) sqlCount(ctx context.Context) (int, error) {
+	rows := &sql.Rows{}
+	selector := uq.sqlQuery()
+	unique := []string{user.FieldID}
+	if len(uq.unique) > 0 {
+		unique = uq.unique
+	}
+	selector.Count(sql.Distinct(selector.Columns(unique...)...))
+	query, args := selector.Query()
+	if err := uq.driver.Query(ctx, query, args, rows); err != nil {
+		return 0, err
+	}
+	defer rows.Close()
+	if !rows.Next() {
+		return 0, errors.New("ent: no rows found")
+	}
+	var n int
+	if err := rows.Scan(&n); err != nil {
+		return 0, fmt.Errorf("ent: failed reading count: %v", err)
+	}
+	return n, nil
+}
+
+func (uq *UserQuery) sqlExist(ctx context.Context) (bool, error) {
+	n, err := uq.sqlCount(ctx)
+	if err != nil {
+		return false, fmt.Errorf("ent: check existence: %v", err)
+	}
+	return n > 0, nil
+}
+
+func (uq *UserQuery) sqlIDs(ctx context.Context) ([]int, error) {
+	vs, err := uq.sqlAll(ctx)
+	if err != nil {
+		return nil, err
+	}
+	var ids []int
+	for _, v := range vs {
+		ids = append(ids, v.ID)
+	}
+	return ids, nil
+}
+
+func (uq *UserQuery) sqlQuery() *sql.Selector {
+	t1 := sql.Table(user.Table)
+	selector := sql.Select(t1.Columns(user.Columns...)...).From(t1)
+	if uq.sql != nil {
+		selector = uq.sql
+		selector.Select(selector.Columns(user.Columns...)...)
+	}
+	for _, p := range uq.predicates {
+		p(selector)
+	}
+	for _, p := range uq.order {
+		p(selector)
+	}
+	if offset := uq.offset; offset != nil {
+		// limit is mandatory for offset clause. We start
+		// with default value, and override it below if needed.
+		selector.Offset(*offset).Limit(math.MaxInt64)
+	}
+	if limit := uq.limit; limit != nil {
+		selector.Limit(*limit)
+	}
+	return selector
+}
+
+// UserQuery is the builder for group-by User entities.
+type UserGroupBy struct {
+	config
+	fields []string
+	fns    []Aggregate
+	// intermediate queries.
+	sql *sql.Selector
+}
+
+// Aggregate adds the given aggregation functions to the group-by query.
+func (ugb *UserGroupBy) Aggregate(fns ...Aggregate) *UserGroupBy {
+	ugb.fns = append(ugb.fns, fns...)
+	return ugb
+}
+
+// Scan applies the group-by query and scan the result into the given value.
+func (ugb *UserGroupBy) Scan(ctx context.Context, v interface{}) error {
+	return ugb.sqlScan(ctx, v)
+}
+
+// ScanX is like Scan, but panics if an error occurs.
+func (ugb *UserGroupBy) ScanX(ctx context.Context, v interface{}) {
+	if err := ugb.Scan(ctx, v); err != nil {
+		panic(err)
+	}
+}
+
+// Strings returns list of strings from group-by. It is only allowed when querying group-by with one field.
+func (ugb *UserGroupBy) Strings(ctx context.Context) ([]string, error) {
+	if len(ugb.fields) > 1 {
+		return nil, errors.New("ent: UserGroupBy.Strings is not achievable when grouping more than 1 field")
+	}
+	var v []string
+	if err := ugb.Scan(ctx, &v); err != nil {
+		return nil, err
+	}
+	return v, nil
+}
+
+// StringsX is like Strings, but panics if an error occurs.
+func (ugb *UserGroupBy) StringsX(ctx context.Context) []string {
+	v, err := ugb.Strings(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+// Ints returns list of ints from group-by. It is only allowed when querying group-by with one field.
+func (ugb *UserGroupBy) Ints(ctx context.Context) ([]int, error) {
+	if len(ugb.fields) > 1 {
+		return nil, errors.New("ent: UserGroupBy.Ints is not achievable when grouping more than 1 field")
+	}
+	var v []int
+	if err := ugb.Scan(ctx, &v); err != nil {
+		return nil, err
+	}
+	return v, nil
+}
+
+// IntsX is like Ints, but panics if an error occurs.
+func (ugb *UserGroupBy) IntsX(ctx context.Context) []int {
+	v, err := ugb.Ints(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+// Float64s returns list of float64s from group-by. It is only allowed when querying group-by with one field.
+func (ugb *UserGroupBy) Float64s(ctx context.Context) ([]float64, error) {
+	if len(ugb.fields) > 1 {
+		return nil, errors.New("ent: UserGroupBy.Float64s is not achievable when grouping more than 1 field")
+	}
+	var v []float64
+	if err := ugb.Scan(ctx, &v); err != nil {
+		return nil, err
+	}
+	return v, nil
+}
+
+// Float64sX is like Float64s, but panics if an error occurs.
+func (ugb *UserGroupBy) Float64sX(ctx context.Context) []float64 {
+	v, err := ugb.Float64s(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+// Bools returns list of bools from group-by. It is only allowed when querying group-by with one field.
+func (ugb *UserGroupBy) Bools(ctx context.Context) ([]bool, error) {
+	if len(ugb.fields) > 1 {
+		return nil, errors.New("ent: UserGroupBy.Bools is not achievable when grouping more than 1 field")
+	}
+	var v []bool
+	if err := ugb.Scan(ctx, &v); err != nil {
+		return nil, err
+	}
+	return v, nil
+}
+
+// BoolsX is like Bools, but panics if an error occurs.
+func (ugb *UserGroupBy) BoolsX(ctx context.Context) []bool {
+	v, err := ugb.Bools(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+func (ugb *UserGroupBy) sqlScan(ctx context.Context, v interface{}) error {
+	rows := &sql.Rows{}
+	query, args := ugb.sqlQuery().Query()
+	if err := ugb.driver.Query(ctx, query, args, rows); err != nil {
+		return err
+	}
+	defer rows.Close()
+	return sql.ScanSlice(rows, v)
+}
+
+func (ugb *UserGroupBy) sqlQuery() *sql.Selector {
+	selector := ugb.sql
+	columns := make([]string, 0, len(ugb.fields)+len(ugb.fns))
+	columns = append(columns, ugb.fields...)
+	for _, fn := range ugb.fns {
+		columns = append(columns, fn.SQL(selector))
+	}
+	return selector.Select(columns...).GroupBy(ugb.fields...)
+}

examples/o2o2types/ent/user_update.go

@@ -0,0 +1,346 @@
+// Code generated (@generated) by entc, DO NOT EDIT.
+
+package ent
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/card"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/predicate"
+	"github.com/facebookincubator/ent/examples/o2o2types/ent/user"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+)
+
+// UserUpdate is the builder for updating User entities.
+type UserUpdate struct {
+	config
+	age         *int
+	name        *string
+	card        map[int]struct{}
+	clearedCard bool
+	predicates  []predicate.User
+}
+
+// Where adds a new predicate for the builder.
+func (uu *UserUpdate) Where(ps ...predicate.User) *UserUpdate {
+	uu.predicates = append(uu.predicates, ps...)
+	return uu
+}
+
+// SetAge sets the age field.
+func (uu *UserUpdate) SetAge(i int) *UserUpdate {
+	uu.age = &i
+	return uu
+}
+
+// SetName sets the name field.
+func (uu *UserUpdate) SetName(s string) *UserUpdate {
+	uu.name = &s
+	return uu
+}
+
+// SetCardID sets the card edge to Card by id.
+func (uu *UserUpdate) SetCardID(id int) *UserUpdate {
+	if uu.card == nil {
+		uu.card = make(map[int]struct{})
+	}
+	uu.card[id] = struct{}{}
+	return uu
+}
+
+// SetNillableCardID sets the card edge to Card by id if the given value is not nil.
+func (uu *UserUpdate) SetNillableCardID(id *int) *UserUpdate {
+	if id != nil {
+		uu = uu.SetCardID(*id)
+	}
+	return uu
+}
+
+// SetCard sets the card edge to Card.
+func (uu *UserUpdate) SetCard(c *Card) *UserUpdate {
+	return uu.SetCardID(c.ID)
+}
+
+// ClearCard clears the card edge to Card.
+func (uu *UserUpdate) ClearCard() *UserUpdate {
+	uu.clearedCard = true
+	return uu
+}
+
+// Save executes the query and returns the number of rows/vertices matched by this operation.
+func (uu *UserUpdate) Save(ctx context.Context) (int, error) {
+	if len(uu.card) > 1 {
+		return 0, errors.New("ent: multiple assignments on a unique edge \"card\"")
+	}
+	return uu.sqlSave(ctx)
+}
+
+// SaveX is like Save, but panics if an error occurs.
+func (uu *UserUpdate) SaveX(ctx context.Context) int {
+	affected, err := uu.Save(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return affected
+}
+
+// Exec executes the query.
+func (uu *UserUpdate) Exec(ctx context.Context) error {
+	_, err := uu.Save(ctx)
+	return err
+}
+
+// ExecX is like Exec, but panics if an error occurs.
+func (uu *UserUpdate) ExecX(ctx context.Context) {
+	if err := uu.Exec(ctx); err != nil {
+		panic(err)
+	}
+}
+
+func (uu *UserUpdate) sqlSave(ctx context.Context) (n int, err error) {
+	selector := sql.Select(user.FieldID).From(sql.Table(user.Table))
+	for _, p := range uu.predicates {
+		p(selector)
+	}
+	rows := &sql.Rows{}
+	query, args := selector.Query()
+	if err = uu.driver.Query(ctx, query, args, rows); err != nil {
+		return 0, err
+	}
+	defer rows.Close()
+	var ids []int
+	for rows.Next() {
+		var id int
+		if err := rows.Scan(&id); err != nil {
+			return 0, fmt.Errorf("ent: failed reading id: %v", err)
+		}
+		ids = append(ids, id)
+	}
+	if len(ids) == 0 {
+		return 0, nil
+	}
+
+	tx, err := uu.driver.Tx(ctx)
+	if err != nil {
+		return 0, err
+	}
+	var (
+		update  bool
+		res     sql.Result
+		builder = sql.Update(user.Table).Where(sql.InInts(user.FieldID, ids...))
+	)
+	if uu.age != nil {
+		update = true
+		builder.Set(user.FieldAge, *uu.age)
+	}
+	if uu.name != nil {
+		update = true
+		builder.Set(user.FieldName, *uu.name)
+	}
+	if update {
+		query, args := builder.Query()
+		if err := tx.Exec(ctx, query, args, &res); err != nil {
+			return 0, rollback(tx, err)
+		}
+	}
+	if uu.clearedCard {
+		query, args := sql.Update(user.CardTable).
+			SetNull(user.CardColumn).
+			Where(sql.InInts(card.FieldID, ids...)).
+			Query()
+		if err := tx.Exec(ctx, query, args, &res); err != nil {
+			return 0, rollback(tx, err)
+		}
+	}
+	if len(uu.card) > 0 {
+		for _, id := range ids {
+			eid := keys(uu.card)[0]
+			query, args := sql.Update(user.CardTable).
+				Set(user.CardColumn, id).
+				Where(sql.EQ(card.FieldID, eid).And().IsNull(user.CardColumn)).
+				Query()
+			if err := tx.Exec(ctx, query, args, &res); err != nil {
+				return 0, rollback(tx, err)
+			}
+			affected, err := res.RowsAffected()
+			if err != nil {
+				return 0, rollback(tx, err)
+			}
+			if int(affected) < len(uu.card) {
+				return 0, rollback(tx, &ErrConstraintFailed{msg: fmt.Sprintf("one of \"card\" %v already connected to a different \"User\"", keys(uu.card))})
+			}
+		}
+	}
+	if err = tx.Commit(); err != nil {
+		return 0, err
+	}
+	return len(ids), nil
+}
+
+// UserUpdateOne is the builder for updating a single User entity.
+type UserUpdateOne struct {
+	config
+	id          int
+	age         *int
+	name        *string
+	card        map[int]struct{}
+	clearedCard bool
+}
+
+// SetAge sets the age field.
+func (uuo *UserUpdateOne) SetAge(i int) *UserUpdateOne {
+	uuo.age = &i
+	return uuo
+}
+
+// SetName sets the name field.
+func (uuo *UserUpdateOne) SetName(s string) *UserUpdateOne {
+	uuo.name = &s
+	return uuo
+}
+
+// SetCardID sets the card edge to Card by id.
+func (uuo *UserUpdateOne) SetCardID(id int) *UserUpdateOne {
+	if uuo.card == nil {
+		uuo.card = make(map[int]struct{})
+	}
+	uuo.card[id] = struct{}{}
+	return uuo
+}
+
+// SetNillableCardID sets the card edge to Card by id if the given value is not nil.
+func (uuo *UserUpdateOne) SetNillableCardID(id *int) *UserUpdateOne {
+	if id != nil {
+		uuo = uuo.SetCardID(*id)
+	}
+	return uuo
+}
+
+// SetCard sets the card edge to Card.
+func (uuo *UserUpdateOne) SetCard(c *Card) *UserUpdateOne {
+	return uuo.SetCardID(c.ID)
+}
+
+// ClearCard clears the card edge to Card.
+func (uuo *UserUpdateOne) ClearCard() *UserUpdateOne {
+	uuo.clearedCard = true
+	return uuo
+}
+
+// Save executes the query and returns the updated entity.
+func (uuo *UserUpdateOne) Save(ctx context.Context) (*User, error) {
+	if len(uuo.card) > 1 {
+		return nil, errors.New("ent: multiple assignments on a unique edge \"card\"")
+	}
+	return uuo.sqlSave(ctx)
+}
+
+// SaveX is like Save, but panics if an error occurs.
+func (uuo *UserUpdateOne) SaveX(ctx context.Context) *User {
+	u, err := uuo.Save(ctx)
+	if err != nil {
+		panic(err)
+	}
+	return u
+}
+
+// Exec executes the query on the entity.
+func (uuo *UserUpdateOne) Exec(ctx context.Context) error {
+	_, err := uuo.Save(ctx)
+	return err
+}
+
+// ExecX is like Exec, but panics if an error occurs.
+func (uuo *UserUpdateOne) ExecX(ctx context.Context) {
+	if err := uuo.Exec(ctx); err != nil {
+		panic(err)
+	}
+}
+
+func (uuo *UserUpdateOne) sqlSave(ctx context.Context) (u *User, err error) {
+	selector := sql.Select(user.Columns...).From(sql.Table(user.Table))
+	user.ID(uuo.id)(selector)
+	rows := &sql.Rows{}
+	query, args := selector.Query()
+	if err = uuo.driver.Query(ctx, query, args, rows); err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var ids []int
+	for rows.Next() {
+		var id int
+		u = &User{config: uuo.config}
+		if err := u.FromRows(rows); err != nil {
+			return nil, fmt.Errorf("ent: failed scanning row into User: %v", err)
+		}
+		id = u.ID
+		ids = append(ids, id)
+	}
+	switch n := len(ids); {
+	case n == 0:
+		return nil, fmt.Errorf("ent: User not found with id: %v", uuo.id)
+	case n > 1:
+		return nil, fmt.Errorf("ent: more than one User with the same id: %v", uuo.id)
+	}
+
+	tx, err := uuo.driver.Tx(ctx)
+	if err != nil {
+		return nil, err
+	}
+	var (
+		update  bool
+		res     sql.Result
+		builder = sql.Update(user.Table).Where(sql.InInts(user.FieldID, ids...))
+	)
+	if uuo.age != nil {
+		update = true
+		builder.Set(user.FieldAge, *uuo.age)
+		u.Age = *uuo.age
+	}
+	if uuo.name != nil {
+		update = true
+		builder.Set(user.FieldName, *uuo.name)
+		u.Name = *uuo.name
+	}
+	if update {
+		query, args := builder.Query()
+		if err := tx.Exec(ctx, query, args, &res); err != nil {
+			return nil, rollback(tx, err)
+		}
+	}
+	if uuo.clearedCard {
+		query, args := sql.Update(user.CardTable).
+			SetNull(user.CardColumn).
+			Where(sql.InInts(card.FieldID, ids...)).
+			Query()
+		if err := tx.Exec(ctx, query, args, &res); err != nil {
+			return nil, rollback(tx, err)
+		}
+	}
+	if len(uuo.card) > 0 {
+		for _, id := range ids {
+			eid := keys(uuo.card)[0]
+			query, args := sql.Update(user.CardTable).
+				Set(user.CardColumn, id).
+				Where(sql.EQ(card.FieldID, eid).And().IsNull(user.CardColumn)).
+				Query()
+			if err := tx.Exec(ctx, query, args, &res); err != nil {
+				return nil, rollback(tx, err)
+			}
+			affected, err := res.RowsAffected()
+			if err != nil {
+				return nil, rollback(tx, err)
+			}
+			if int(affected) < len(uuo.card) {
+				return nil, rollback(tx, &ErrConstraintFailed{msg: fmt.Sprintf("one of \"card\" %v already connected to a different \"User\"", keys(uuo.card))})
+			}
+		}
+	}
+	if err = tx.Commit(); err != nil {
+		return nil, err
+	}
+	return u, nil
+}

examples/o2o2types/o2o2types.go

@@ -0,0 +1,67 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"time"
+
+	"github.com/facebookincubator/ent/examples/o2o2types/ent"
+
+	"github.com/facebookincubator/ent/dialect/sql"
+	_ "github.com/mattn/go-sqlite3"
+)
+
+func main() {
+	db, err := sql.Open("sqlite3", "file:o2o2types?mode=memory&cache=shared&_fk=1")
+	if err != nil {
+		log.Fatalf("failed opening connection to sqlite: %v", err)
+	}
+	defer db.Close()
+	client := ent.NewClient(ent.Driver(db))
+	ctx := context.Background()
+	// run the auto migration tool.
+	if err := client.Schema.Create(ctx); err != nil {
+		log.Fatalf("failed creating schema resources: %v", err)
+	}
+	if err := Do(ctx, client); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func Do(ctx context.Context, client *ent.Client) error {
+	a8m, err := client.User.
+		Create().
+		SetAge(30).
+		SetName("Mashraki").
+		Save(ctx)
+	if err != nil {
+		return fmt.Errorf("creating user: %v", err)
+	}
+	log.Println("user:", a8m)
+	card1, err := client.Card.
+		Create().
+		SetOwner(a8m).
+		SetNumber("1020").
+		SetExpired(time.Now().Add(time.Minute)).
+		Save(ctx)
+	if err != nil {
+		return fmt.Errorf("creating card: %v", err)
+	}
+	log.Println("card:", card1)
+	// Only returns the card of the user,
+	// and expects that there's only one.
+	card2, err := a8m.QueryCard().Only(ctx)
+	if err != nil {
+		return fmt.Errorf("querying card: %v", err)
+	}
+	log.Println("card:", card2)
+	// The Card entity is able to query its owner using
+	// its back-reference.
+	owner, err := card2.QueryOwner().Only(ctx)
+	if err != nil {
+		return fmt.Errorf("querying owner: %v", err)
+	}
+	log.Println("owner:", owner)
+	return nil
+}