Locale
======

Validates that a value is a valid locale.

The "value" for each locale is any of the `ICU format locale IDs`_. For example,
the two letter `ISO 639-1`_ *language* code (e.g. ``fr``), or the language code
followed by an underscore (``_``) and the `ISO 3166-1 alpha-2`_ *country* code
(e.g. ``fr_FR`` for French/France).

The given locale values are *canonicalized* before validating them to avoid
issues with wrong uppercase/lowercase values and to remove unneeded elements
(e.g. ``FR-fr.utf8`` will be validated as ``fr_FR``).

==========  ===================================================================
Applies to  :ref:`property or method <validation-property-target>`
Class       :class:`Symfony\\Component\\Validator\\Constraints\\Locale`
Validator   :class:`Symfony\\Component\\Validator\\Constraints\\LocaleValidator`
==========  ===================================================================

Basic Usage
-----------

.. configuration-block::

    .. code-block:: php-attributes

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

        use Symfony\Component\Validator\Constraints as Assert;

        class User
        {
            #[Assert\Locale(
                canonicalize: true,
            )]
            protected string $locale;
        }

    .. code-block:: yaml

        # config/validator/validation.yaml
        App\Entity\User:
            properties:
                locale:
                    - Locale:
                        canonicalize: true

    .. 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\User">
                <property name="locale">
                    <constraint name="Locale">
                        <option name="canonicalize">true</option>
                    </constraint>
                </property>
            </class>
        </constraint-mapping>

    .. code-block:: php

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

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

        class User
        {
            // ...

            public static function loadValidatorMetadata(ClassMetadata $metadata): void
            {
                $metadata->addPropertyConstraint('locale', new Assert\Locale([
                    'canonicalize' => true,
                ]));
            }
        }

.. include:: /reference/constraints/_empty-values-are-valid.rst.inc

Options
-------

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

``message``
~~~~~~~~~~~

**type**: ``string`` **default**: ``This value is not a valid locale.``

This message is shown if the string is not a valid locale.

You can use the following parameters in this message:

===============  ==============================================================
Parameter        Description
===============  ==============================================================
``{{ value }}``  The current (invalid) value
``{{ label }}``  Corresponding form field label
===============  ==============================================================

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

.. _`ICU format locale IDs`: https://unicode-org.github.io/icu/userguide/locale/
.. _`ISO 639-1`: https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes
.. _`ISO 3166-1 alpha-2`: https://en.wikipedia.org/wiki/ISO_3166-1#Current_codes
