entc/gen: allow selecting specific fields (#1075)

examples/m2m2types/ent/group.go

@@ -45,29 +45,42 @@ func (e GroupEdges) UsersOrErr() ([]*User, error) {
 }
 
 // scanValues returns the types for scanning values from sql.Rows.
-func (*Group) scanValues() []interface{} {
-	return []interface{}{
-		&sql.NullInt64{},  // id
-		&sql.NullString{}, // name
+func (*Group) scanValues(columns []string) ([]interface{}, error) {
+	values := make([]interface{}, len(columns))
+	for i := range columns {
+		switch columns[i] {
+		case group.FieldID:
+			values[i] = &sql.NullInt64{}
+		case group.FieldName:
+			values[i] = &sql.NullString{}
+		default:
+			return nil, fmt.Errorf("unexpected column %q for type Group", columns[i])
+		}
 	}
+	return values, nil
 }
 
 // assignValues assigns the values that were returned from sql.Rows (after scanning)
 // to the Group fields.
-func (gr *Group) assignValues(values ...interface{}) error {
-	if m, n := len(values), len(group.Columns); m < n {
+func (gr *Group) assignValues(columns []string, values []interface{}) error {
+	if m, n := len(values), len(columns); m < n {
 		return fmt.Errorf("mismatch number of scan values: %d != %d", m, n)
 	}
-	value, ok := values[0].(*sql.NullInt64)
-	if !ok {
-		return fmt.Errorf("unexpected type %T for field id", value)
-	}
-	gr.ID = int(value.Int64)
-	values = values[1:]
-	if value, ok := values[0].(*sql.NullString); !ok {
-		return fmt.Errorf("unexpected type %T for field name", values[0])
-	} else if value.Valid {
-		gr.Name = value.String
+	for i := range columns {
+		switch columns[i] {
+		case group.FieldID:
+			value, ok := values[i].(*sql.NullInt64)
+			if !ok {
+				return fmt.Errorf("unexpected type %T for field id", value)
+			}
+			gr.ID = int(value.Int64)
+		case group.FieldName:
+			if value, ok := values[i].(*sql.NullString); !ok {
+				return fmt.Errorf("unexpected type %T for field name", values[i])
+			} else if value.Valid {
+				gr.Name = value.String
+			}
+		}
 	}
 	return nil
 }

examples/m2m2types/ent/group_query.go

@@ -344,19 +344,18 @@ func (gq *GroupQuery) sqlAll(ctx context.Context) ([]*Group, error) {
 			gq.withUsers != nil,
 		}
 	)
-	_spec.ScanValues = func() []interface{} {
+	_spec.ScanValues = func(columns []string) ([]interface{}, error) {
 		node := &Group{config: gq.config}
 		nodes = append(nodes, node)
-		values := node.scanValues()
-		return values
+		return node.scanValues(columns)
 	}
-	_spec.Assign = func(values ...interface{}) error {
+	_spec.Assign = func(columns []string, values []interface{}) error {
 		if len(nodes) == 0 {
 			return fmt.Errorf("ent: Assign called without calling ScanValues")
 		}
 		node := nodes[len(nodes)-1]
 		node.Edges.loadedTypes = loadedTypes
-		return node.assignValues(values...)
+		return node.assignValues(columns, values)
 	}
 	if err := sqlgraph.QueryNodes(ctx, gq.driver, _spec); err != nil {
 		return nil, err

examples/m2m2types/ent/group_update.go

@@ -403,7 +403,7 @@ func (guo *GroupUpdateOne) sqlSave(ctx context.Context) (_node *Group, err error
 	}
 	_node = &Group{config: guo.config}
 	_spec.Assign = _node.assignValues
-	_spec.ScanValues = _node.scanValues()
+	_spec.ScanValues = _node.scanValues
 	if err = sqlgraph.UpdateNode(ctx, guo.driver, _spec); err != nil {
 		if _, ok := err.(*sqlgraph.NotFoundError); ok {
 			err = &NotFoundError{group.Label}

examples/m2m2types/ent/user.go

@@ -47,35 +47,48 @@ func (e UserEdges) GroupsOrErr() ([]*Group, error) {
 }
 
 // scanValues returns the types for scanning values from sql.Rows.
-func (*User) scanValues() []interface{} {
-	return []interface{}{
-		&sql.NullInt64{},  // id
-		&sql.NullInt64{},  // age
-		&sql.NullString{}, // name
+func (*User) scanValues(columns []string) ([]interface{}, error) {
+	values := make([]interface{}, len(columns))
+	for i := range columns {
+		switch columns[i] {
+		case user.FieldID, user.FieldAge:
+			values[i] = &sql.NullInt64{}
+		case user.FieldName:
+			values[i] = &sql.NullString{}
+		default:
+			return nil, fmt.Errorf("unexpected column %q for type User", columns[i])
+		}
 	}
+	return values, nil
 }
 
 // assignValues assigns the values that were returned from sql.Rows (after scanning)
 // to the User fields.
-func (u *User) assignValues(values ...interface{}) error {
-	if m, n := len(values), len(user.Columns); m < n {
+func (u *User) assignValues(columns []string, values []interface{}) error {
+	if m, n := len(values), len(columns); m < n {
 		return fmt.Errorf("mismatch number of scan values: %d != %d", m, n)
 	}
-	value, ok := values[0].(*sql.NullInt64)
-	if !ok {
-		return fmt.Errorf("unexpected type %T for field id", value)
-	}
-	u.ID = int(value.Int64)
-	values = values[1:]
-	if value, ok := values[0].(*sql.NullInt64); !ok {
-		return fmt.Errorf("unexpected type %T for field age", values[0])
-	} else if value.Valid {
-		u.Age = int(value.Int64)
-	}
-	if value, ok := values[1].(*sql.NullString); !ok {
-		return fmt.Errorf("unexpected type %T for field name", values[1])
-	} else if value.Valid {
-		u.Name = value.String
+	for i := range columns {
+		switch columns[i] {
+		case user.FieldID:
+			value, ok := values[i].(*sql.NullInt64)
+			if !ok {
+				return fmt.Errorf("unexpected type %T for field id", value)
+			}
+			u.ID = int(value.Int64)
+		case user.FieldAge:
+			if value, ok := values[i].(*sql.NullInt64); !ok {
+				return fmt.Errorf("unexpected type %T for field age", values[i])
+			} else if value.Valid {
+				u.Age = int(value.Int64)
+			}
+		case user.FieldName:
+			if value, ok := values[i].(*sql.NullString); !ok {
+				return fmt.Errorf("unexpected type %T for field name", values[i])
+			} else if value.Valid {
+				u.Name = value.String
+			}
+		}
 	}
 	return nil
 }

examples/m2m2types/ent/user_query.go

@@ -344,19 +344,18 @@ func (uq *UserQuery) sqlAll(ctx context.Context) ([]*User, error) {
 			uq.withGroups != nil,
 		}
 	)
-	_spec.ScanValues = func() []interface{} {
+	_spec.ScanValues = func(columns []string) ([]interface{}, error) {
 		node := &User{config: uq.config}
 		nodes = append(nodes, node)
-		values := node.scanValues()
-		return values
+		return node.scanValues(columns)
 	}
-	_spec.Assign = func(values ...interface{}) error {
+	_spec.Assign = func(columns []string, values []interface{}) error {
 		if len(nodes) == 0 {
 			return fmt.Errorf("ent: Assign called without calling ScanValues")
 		}
 		node := nodes[len(nodes)-1]
 		node.Edges.loadedTypes = loadedTypes
-		return node.assignValues(values...)
+		return node.assignValues(columns, values)
 	}
 	if err := sqlgraph.QueryNodes(ctx, uq.driver, _spec); err != nil {
 		return nil, err

examples/m2m2types/ent/user_update.go

@@ -457,7 +457,7 @@ func (uuo *UserUpdateOne) sqlSave(ctx context.Context) (_node *User, err error)
 	}
 	_node = &User{config: uuo.config}
 	_spec.Assign = _node.assignValues
-	_spec.ScanValues = _node.scanValues()
+	_spec.ScanValues = _node.scanValues
 	if err = sqlgraph.UpdateNode(ctx, uuo.driver, _spec); err != nil {
 		if _, ok := err.(*sqlgraph.NotFoundError); ok {
 			err = &NotFoundError{user.Label}