Class yii\validators\ExistValidator

ExistValidator validates that the attribute value exists in a table.

ExistValidator checks if the value being validated can be found in the table column specified by the ActiveRecord class $targetClass and the attribute $targetAttribute. Since version 2.0.14 you can use more convenient attribute $targetRelation

This validator is often used to verify that a foreign key contains a value that can be found in the foreign table.

The following are examples of validation rules using this validator:

// a1 needs to exist
['a1', 'exist']
// a1 needs to exist, but its value will use a2 to check for the existence
['a1', 'exist', 'targetAttribute' => 'a2']
// a1 and a2 need to exist together, and they both will receive error message
[['a1', 'a2'], 'exist', 'targetAttribute' => ['a1', 'a2']]
// a1 and a2 need to exist together, only a1 will receive error message
['a1', 'exist', 'targetAttribute' => ['a1', 'a2']]
// a1 needs to exist by checking the existence of both a2 and a3 (using a1 value)
['a1', 'exist', 'targetAttribute' => ['a2', 'a1' => 'a3']]
// type_id needs to exist in the column "id" in the table defined in ProductType class
['type_id', 'exist', 'targetClass' => ProductType::class, 'targetAttribute' => ['type_id' => 'id']],
// the same as the previous, but using already defined relation "type"
['type_id', 'exist', 'targetRelation' => 'type'],