Unique
======

Validates that all the elements of the given collection are unique (none of them
is present more than once). Elements are compared strictly, so ``'7'`` and ``7``
are considered different elements (a string and an integer, respectively).

.. seealso::

    If you want to apply different validation constraints to the elements of a
    collection or want to make sure that certain collection keys are present,
    use the :doc:`Collection constraint </reference/constraints/Collection>`.

.. seealso::

    If you want to validate that the value of an entity property is unique among
    all entities of the same type (e.g. the registration email of all users) use
    the :doc:`UniqueEntity constraint </reference/constraints/UniqueEntity>`.

==========  ===================================================================
Applies to  :ref:`property or method <validation-property-target>`
Options     - `groups`_
            - `message`_
            - `payload`_
Class       :class:`Symfony\\Component\\Validator\\Constraints\\Unique`
Validator   :class:`Symfony\\Component\\Validator\\Constraints\\UniqueValidator`
==========  ===================================================================

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:

.. configuration-block::

    .. code-block:: php-annotations

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

        use Symfony\Component\Validator\Constraints as Assert;

        class Person
        {
            /**
             * @Assert\Unique
             */
            protected $contactEmails;
        }

    .. code-block:: yaml

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

    .. code-block:: xml

        <!-- 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>

    .. code-block:: php

        // 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)
            {
                $metadata->addPropertyConstraint('contactEmails', new Assert\Unique());
            }
        }

Options
-------

.. include:: /reference/constraints/_groups-option.rst.inc

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 repeated value
=============================  ================================================

.. include:: /reference/constraints/_payload-option.rst.inc