[Validator] add documentation for the new Timezone constraint.

reference/constraints.rst

@@ -49,6 +49,7 @@ Validation Constraints Reference
    constraints/Language
    constraints/Locale
    constraints/Country
+   constraints/Timezone
 
    constraints/File
    constraints/Image

reference/constraints/Timezone.rst

@@ -0,0 +1,144 @@
+Timezone
+========
+
+Validates that a value is a valid timezone identifier (e.g. ``Europe/Paris``).
+
+==========  ======================================================================
+Applies to  :ref:`property or method <validation-property-target>`
+Options     - `groups`_
+            - `message`_
+            - `payload`_
+            - `zone`_
+            - `countryCode`_
+Class       :class:`Symfony\\Component\\Validator\\Constraints\\Timezone`
+Validator   :class:`Symfony\\Component\\Validator\\Constraints\\TimezoneValidator`
+==========  ======================================================================
+
+Basic Usage
+-----------
+
+Suppose you have a ``UserSettings`` class, with a ``timezone`` field that is a
+string meant to contain a timezone identifier (e.g. ``America/New_York``):
+
+.. configuration-block::
+
+    .. code-block:: php-annotations
+
+        // src/Entity/UserSettings.php
+        namespace App\Entity;
+
+        use Symfony\Component\Validator\Constraints as Assert;
+
+        class UserSettings
+        {
+            /**
+             * @Assert\Timezone
+             */
+             protected $timezone;
+        }
+
+    .. code-block:: yaml
+
+        # config/validator/validation.yaml
+        App\Entity\UserSettings:
+            properties:
+                timezone:
+                    - Timezone: ~
+
+    .. 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\UserSettings">
+                <property name="timezone">
+                    <constraint name="Timezone"/>
+                </property>
+            </class>
+        </constraint-mapping>
+
+    .. code-block:: php
+
+        // src/Entity/UserSettings.php
+        namespace App\Entity;
+
+        use Symfony\Component\Validator\Mapping\ClassMetadata;
+        use Symfony\Component\Validator\Constraints as Assert;
+
+        class UserSettings
+        {
+            protected $timezone;
+
+            public static function loadValidatorMetadata(ClassMetadata $metadata)
+            {
+                $metadata->addPropertyConstraint('timezone', new Assert\Timezone());
+            }
+        }
+
+.. 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 timezone.``
+
+This message is shown if the underlying data is not a valid timezone identifier.
+
+You can use the following parameters in this message:
+
+===============  ==============================================================
+Parameter        Description
+===============  ==============================================================
+``{{ value }}``  The current (invalid) value
+===============  ==============================================================
+
+.. include:: /reference/constraints/_payload-option.rst.inc
+
+zone
+~~~~
+
+**type**: ``string`` **default**: ``\DateTimeZone::ALL``
+
+Set this option to any of the following constants to restrict the valid timezone
+identifiers to the ones that belong to that geographical zone:
+
+* ``\DateTimeZone::AFRICA``
+* ``\DateTimeZone::AMERICA``
+* ``\DateTimeZone::ANTARCTICA``
+* ``\DateTimeZone::ARCTIC``
+* ``\DateTimeZone::ASIA``
+* ``\DateTimeZone::ATLANTIC``
+* ``\DateTimeZone::AUSTRALIA``
+* ``\DateTimeZone::EUROPE``
+* ``\DateTimeZone::INDIAN``
+* ``\DateTimeZone::PACIFIC``
+
+The special ``\DateTimeZone::ALL`` zone accepts any timezone excluding deprecated timezones.
+
+The special ``\DateTimeZone::ALL_WITH_BC`` zone accepts any timezone including deprecated timezones.
+
+The special ``\DateTimeZone::PER_COUNTRY`` zone limits the timezones to a certain country. This zone
+value must be used in combination with the ``countryCode`` option.
+
+countryCode
+~~~~~~~~~~~
+
+**type**: ``string`` **default**: ``null``
+
+If the ``zone`` option is set to ``\DateTimeZone::PER_COUNTRY``, this option
+restricts the valid timezone identifiers to the ones that belong to the given
+country.
+
+The value of this option must be a valid `ISO 3166-1 alpha-2`_ country code
+(e.g. ``CN`` for China).
+
+.. _`DateTimeZone`: https://www.php.net/datetimezone
+.. _`ISO 3166-1 alpha-2`: https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2

reference/constraints/map.rst.inc

@@ -60,6 +60,7 @@ Choice Constraints
 * :doc:`Language </reference/constraints/Language>`
 * :doc:`Locale </reference/constraints/Locale>`
 * :doc:`Country </reference/constraints/Country>`
+* :doc:`Timezone </reference/constraints/Timezone>`
 
 File Constraints
 ~~~~~~~~~~~~~~~~