ent/doc/md/predicates.md

id, title

id	title
predicates	Predicates

Field Predicates

• Bool:
  • =, !=
• Numeric:
  • =, !=, >, <, >=, <=,
  • IN, NOT IN
• Time:
  • =, !=, >, <, >=, <=
  • IN, NOT IN
• String:
  • =, !=, >, <, >=, <=
  • IN, NOT IN
  • Contains, HasPrefix, HasSuffix
  • ContainsFold, EqualFold (SQL specific)
• JSON
  • =, !=
  • =, !=, >, <, >=, <= on nested values (JSON path).
  • Contains on nested values (JSON path).
  • HasKey, Len<P>
• Optional fields:
  • IsNil, NotNil

Edge Predicates

• HasEdge. For example, for edge named owner of type Pet, use:

   client.Pet.
    	Query().
    	Where(pet.HasOwner()).
    	All(ctx)
  

• HasEdgeWith. Add list of predicates for edge predicate.

   client.Pet.
    	Query().
    	Where(pet.HasOwnerWith(user.Name("a8m"))).
    	All(ctx)
  

Negation (NOT)

client.Pet.
	Query().
	Where(pet.Not(pet.NameHasPrefix("Ari"))).
	All(ctx)

Disjunction (OR)

client.Pet.
	Query().
	Where(
		pet.Or(
			pet.HasOwner(),
			pet.Not(pet.HasFriends()),
		)
	).
	All(ctx)

Conjunction (AND)

client.Pet.
	Query().
	Where(
		pet.And(
			pet.HasOwner(),
			pet.Not(pet.HasFriends()),
		)
	).
	All(ctx)

Custom Predicates

Custom predicates can be useful if you want to write your own dialect-specific logic or to control the executed queries.

Get all pets of users 1, 2 and 3

pets := client.Pet.
	Query().
	Where(func(s *sql.Selector) {
		s.Where(sql.InInts(pet.FieldOwnerID, 1, 2, 3))
	}).
	AllX(ctx)

The above code will produce the following SQL query:

SELECT DISTINCT `pets`.`id`, `pets`.`owner_id` FROM `pets` WHERE `owner_id` IN (1, 2, 3)

Count the number of users whose JSON field named URL contains the Scheme key

count := client.User.
	Query().
	Where(func(s *sql.Selector) {
		s.Where(sqljson.HasKey(user.FieldURL, sqljson.Path("Scheme")))
	}).
	CountX(ctx)

The above code will produce the following SQL query:

-- PostgreSQL
SELECT COUNT(DISTINCT "users"."id") FROM "users" WHERE "url"->'Scheme' IS NOT NULL

-- SQLite and MySQL
SELECT COUNT(DISTINCT `users`.`id`) FROM `users` WHERE JSON_EXTRACT(`url`, "$.Scheme") IS NOT NULL

Get all users with a "Tesla" car

Consider an ent query such as:

users := client.User.Query().
	Where(user.HasCarWith(car.Model("Tesla"))).
	AllX(ctx)

This query can be rephrased in 3 different forms: IN, EXISTS and JOIN.

// `IN` version.
users := client.User.Query().
	Where(func(s *sql.Selector) {
		t := sql.Table(car.Table)
        s.Where(
            sql.In(
                s.C(user.FieldID),
                sql.Select(t.C(user.FieldID)).From(t).Where(sql.EQ(t.C(car.FieldModel), "Tesla")),
            ),
        )
	}).
	AllX(ctx)

// `JOIN` version.
users := client.User.Query().
	Where(func(s *sql.Selector) {
		t := sql.Table(car.Table)
		s.Join(t).On(s.C(user.FieldID), t.C(car.FieldOwnerID))
		s.Where(sql.EQ(t.C(car.FieldModel), "Tesla"))
	}).
	AllX(ctx)

// `EXISTS` version.
users := client.User.Query().
	Where(func(s *sql.Selector) {
		t := sql.Table(car.Table)
		p := sql.And(
            sql.EQ(t.C(car.FieldModel), "Tesla"),
			sql.ColumnsEQ(s.C(user.FieldID), t.C(car.FieldOwnerID)),
		)
		s.Where(sql.Exists(sql.Select().From(t).Where(p)))
	}).
	AllX(ctx)

The above code will produce the following SQL query:

-- `IN` version.
SELECT DISTINCT `users`.`id`, `users`.`age`, `users`.`name` FROM `users` WHERE `users`.`id` IN (SELECT `cars`.`id` FROM `cars` WHERE `cars`.`model` = 'Tesla')

-- `JOIN` version.
SELECT DISTINCT `users`.`id`, `users`.`age`, `users`.`name` FROM `users` JOIN `cars` ON `users`.`id` = `cars`.`owner_id` WHERE `cars`.`model` = 'Tesla'

-- `EXISTS` version.
SELECT DISTINCT `users`.`id`, `users`.`age`, `users`.`name` FROM `users` WHERE EXISTS (SELECT * FROM `cars` WHERE `cars`.`model` = 'Tesla' AND `users`.`id` = `cars`.`owner_id`)