minor #20532 [Validator] Add Slug constraint (tcoch)

This PR was squashed before being merged into the 7.3 branch.

Discussion
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[Validator] Add Slug constraint

Fix #20527

Commits
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b4f8f6b [Validator] Add Slug constraint

Author: javiereguiluz

Diff for: reference/constraints/Slug.rst

@@ -0,0 +1,119 @@
+Slug
+====
+
+.. versionadded:: 7.3
+
+    The ``Slug`` constraint was introduced in Symfony 7.3.
+
+Validates that a value is a slug.
+A slug is a string that, by default, matches the regex ``/^[a-z0-9]+(?:-[a-z0-9]+)*$/``.
+
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
+==========  ===================================================================
+Applies to  :ref:`property or method <validation-property-target>`
+Class       :class:`Symfony\\Component\\Validator\\Constraints\\Slug`
+Validator   :class:`Symfony\\Component\\Validator\\Constraints\\SlugValidator`
+==========  ===================================================================
+
+Basic Usage
+-----------
+
+The ``Slug`` constraint can be applied to a property or a "getter" method:
+
+.. configuration-block::
+
+    .. code-block:: php-attributes
+
+        // src/Entity/Author.php
+        namespace App\Entity;
+
+        use Symfony\Component\Validator\Constraints as Assert;
+
+        class Author
+        {
+            #[Assert\Slug]
+            protected string $slug;
+        }
+
+    .. code-block:: yaml
+
+        # config/validator/validation.yaml
+        App\Entity\Author:
+            properties:
+                slug:
+                    - Slug: ~
+
+    .. 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\Author">
+                <property name="slug">
+                    <constraint name="Slug"/>
+                </property>
+            </class>
+        </constraint-mapping>
+
+    .. code-block:: php
+
+        // src/Entity/Author.php
+        namespace App\Entity;
+
+        use Symfony\Component\Validator\Constraints as Assert;
+        use Symfony\Component\Validator\Mapping\ClassMetadata;
+
+        class Author
+        {
+            // ...
+
+            public static function loadValidatorMetadata(ClassMetadata $metadata): void
+            {
+                $metadata->addPropertyConstraint('slug', new Assert\Slug());
+            }
+        }
+
+Examples of valid values :
+
+* foobar
+* foo-bar
+* foo123
+* foo-123bar
+
+Upper case characters would result in an violation of this constraint.
+
+Options
+-------
+
+``regex``
+~~~~~~~~~
+
+**type**: ``string`` default: ``/^[a-z0-9]+(?:-[a-z0-9]+)*$/``
+
+This option allows you to modify the regular expression pattern that the input will be matched against
+via the :phpfunction:`preg_match` PHP function.
+
+If you need to use it, you might also want to take a look at the :doc:`Regex constraint <Regex>`.
+
+``message``
+~~~~~~~~~~~
+
+**type**: ``string`` **default**: ``This value is not a valid slug``
+
+This is the message that will be shown if this validator fails.
+
+You can use the following parameters in this message:
+
+=================  ==============================================================
+Parameter          Description
+=================  ==============================================================
+``{{ value }}``    The current (invalid) value
+=================  ==============================================================
+
+.. include:: /reference/constraints/_groups-option.rst.inc
+
+.. include:: /reference/constraints/_payload-option.rst.inc

Diff for: reference/constraints/map.rst.inc

@@ -33,6 +33,7 @@ String Constraints
 * :doc:`NotCompromisedPassword </reference/constraints/NotCompromisedPassword>`
 * :doc:`PasswordStrength </reference/constraints/PasswordStrength>`
 * :doc:`Regex </reference/constraints/Regex>`
+* :doc:`Slug </reference/constraints/Slug>`
 * :doc:`Ulid </reference/constraints/Ulid>`
 * :doc:`Url </reference/constraints/Url>`
 * :doc:`UserPassword </reference/constraints/UserPassword>`