Unique

Validates that all the elements of the given collection are unique (none of them is present more than once). By default elements are compared strictly, so '7' and 7 are considered different elements (a string and an integer, respectively). If you want to apply any other comparison logic, use the normalizer option.

Basic Usage

This constraint can be applied to any property of type array or \Traversable. In the following example, $contactEmails is an array of strings:

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        // src/Entity/Person.php
namespace App\Entity;

use Symfony\Component\Validator\Constraints as Assert;

class Person
{
    #[Assert\Unique]
    protected array $contactEmails;
}
    

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        # config/validator/validation.yaml
App\Entity\Person:
    properties:
        contactEmails:
            - Unique: ~
    

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        <!-- config/validator/validation.xml -->
<?xml version="1.0" encoding="UTF-8" ?>
<constraint-mapping xmlns="http://symfony.com/schema/dic/constraint-mapping"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping https://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">

    <class name="App\Entity\Person">
        <property name="contactEmails">
            <constraint name="Unique"/>
        </property>
    </class>
</constraint-mapping>
    

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        // src/Entity/Person.php
namespace App\Entity;

use Symfony\Component\Validator\Constraints as Assert;
use Symfony\Component\Validator\Mapping\ClassMetadata;

class Person
{
    // ...

    public static function loadValidatorMetadata(ClassMetadata $metadata): void
    {
        $metadata->addPropertyConstraint('contactEmails', new Assert\Unique());
    }
}
    

Options

`fields`

type: array | string

This is defines the key or keys in a collection that should be checked for uniqueness. By default, all collection keys are checked for uniqueness.

For instance, assume you have a collection of items that contain a latitude, longitude and label fields. By default, you can have duplicate coordinates as long as the label is different. By setting the fields option, you can force latitude+longitude to be unique in the collection:

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        // src/Entity/PointOfInterest.php
namespace App\Entity;

use Symfony\Component\Validator\Constraints as Assert;

class PointOfInterest
{
    #[Assert\Unique(fields: ['latitude', 'longitude'])]
    protected array $coordinates;
}
    

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        # config/validator/validation.yaml
App\Entity\PointOfInterest:
    properties:
        coordinates:
            - Unique:
                  fields: [latitude, longitude]
    

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        <!-- config/validator/validation.xml -->
<?xml version="1.0" encoding="UTF-8" ?>
<constraint-mapping xmlns="http://symfony.com/schema/dic/constraint-mapping"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping https://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">

    <class name="App\Entity\PointOfInterest">
        <property name="coordinates">
            <constraint name="Unique">
                <option name="fields">
                    <value>latitude</value>
                    <value>longitude</value>
                </option>
            </constraint>
        </property>
    </class>
</constraint-mapping>
    

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        // src/Entity/PointOfInterest.php
namespace App\Entity;

use Symfony\Component\Validator\Constraints as Assert;
use Symfony\Component\Validator\Mapping\ClassMetadata;

class PointOfInterest
{
    // ...

    public static function loadValidatorMetadata(ClassMetadata $metadata): void
    {
        $metadata->addPropertyConstraint('coordinates', new Assert\Unique([
            'fields' => ['latitude', 'longitude'],
        ]));
    }
}
    

`groups`

type: array | string default: null

It defines the validation group or groups of this constraint. Read more about validation groups.

`message`

type: string default: This collection should contain only unique elements.

This is the message that will be shown if at least one element is repeated in the collection.

You can use the following parameters in this message:

Parameter	Description
`{{ value }}`	The current (invalid) value

`normalizer`

type: a PHP callable default: null

This option defined the PHP callable applied to each element of the given collection before checking if the collection is valid.

For example, you can pass the 'trim' string to apply the trim PHP function to each element of the collection in order to ignore leading and trailing whitespace during validation.

`payload`

type: mixed default: null

This option can be used to attach arbitrary domain-specific data to a constraint. The configured payload is not used by the Validator component, but its processing is completely up to you.

For example, you may want to use several error levels to present failed constraints differently in the front-end depending on the severity of the error.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.

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Applies to	property or method
Class	Unique
Validator	UniqueValidator