[Validator] Add the Yaml constraint

Author: javiereguiluz

components/yaml.rst

@@ -214,6 +214,8 @@ During the parsing of the YAML contents, all the ``_`` characters are removed
 from the numeric literal contents, so there is not a limit in the number of
 underscores you can include or the way you group contents.
 
+.. _yaml-flags:
+
 Advanced Usage: Flags
 ---------------------
 

reference/constraints/Yaml.rst

@@ -0,0 +1,152 @@
+Yaml
+====
+
+Validates that a value has valid `YAML`_ syntax.
+
+.. versionadded:: 7.2
+
+    The ``Yaml`` constraint was introduced in Symfony 7.2.
+
+==========  ===================================================================
+Applies to  :ref:`property or method <validation-property-target>`
+Class       :class:`Symfony\\Component\\Validator\\Constraints\\Yaml`
+Validator   :class:`Symfony\\Component\\Validator\\Constraints\\YamlValidator`
+==========  ===================================================================
+
+Basic Usage
+-----------
+
+The ``Yaml`` constraint can be applied to a property or a "getter" method:
+
+.. configuration-block::
+
+    .. code-block:: php-attributes
+
+        // src/Entity/Report.php
+        namespace App\Entity;
+
+        use Symfony\Component\Validator\Constraints as Assert;
+
+        class Report
+        {
+            #[Assert\Yaml(
+                message: "Your configuration doesn't have valid YAML syntax."
+            )]
+            private string $customConfiguration;
+        }
+
+    .. code-block:: yaml
+
+        # config/validator/validation.yaml
+        App\Entity\Report:
+            properties:
+                customConfiguration:
+                    - Yaml:
+                        message: Your configuration doesn't have valid YAML syntax.
+
+    .. 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\Report">
+                <property name="customConfiguration">
+                    <constraint name="Yaml">
+                        <option name="message">Your configuration doesn't have valid YAML syntax.</option>
+                    </constraint>
+                </property>
+            </class>
+        </constraint-mapping>
+
+    .. code-block:: php
+
+        // src/Entity/Report.php
+        namespace App\Entity;
+
+        use Symfony\Component\Validator\Constraints as Assert;
+        use Symfony\Component\Validator\Mapping\ClassMetadata;
+
+        class Report
+        {
+            public static function loadValidatorMetadata(ClassMetadata $metadata): void
+            {
+                $metadata->addPropertyConstraint('customConfiguration', new Assert\Yaml([
+                    'message' => 'Your configuration doesn\'t have valid YAML syntax.',
+                ]));
+            }
+        }
+
+Options
+-------
+
+``flags``
+~~~~~~~~~
+
+**type**: ``integer`` **default**: ``0``
+
+This option enables optional features of the YAML parser when validating contents.
+Its value is a combination of one or more of the :ref:`flags defined by the Yaml component <yaml-flags>`:
+
+.. configuration-block::
+
+    .. code-block:: php-attributes
+
+        // src/Entity/Report.php
+        namespace App\Entity;
+
+        use Symfony\Component\Validator\Constraints as Assert;
+        use Symfony\Component\Yaml\Yaml;
+
+        class Report
+        {
+            #[Assert\Yaml(
+                message: "Your configuration doesn't have valid YAML syntax.",
+                flags: Yaml::PARSE_CONSTANT | Yaml::PARSE_CUSTOM_TAGS | Yaml::PARSE_DATETIME,
+            )]
+            private string $customConfiguration;
+        }
+
+    .. code-block:: php
+
+        // src/Entity/Report.php
+        namespace App\Entity;
+
+        use Symfony\Component\Validator\Constraints as Assert;
+        use Symfony\Component\Validator\Mapping\ClassMetadata;
+        use Symfony\Component\Yaml\Yaml;
+
+        class Report
+        {
+            public static function loadValidatorMetadata(ClassMetadata $metadata): void
+            {
+                $metadata->addPropertyConstraint('customConfiguration', new Assert\Yaml([
+                    'message' => 'Your configuration doesn\'t have valid YAML syntax.',
+                    'flags' => Yaml::PARSE_CONSTANT | Yaml::PARSE_CUSTOM_TAGS | Yaml::PARSE_DATETIME,
+                ]));
+            }
+        }
+
+``message``
+~~~~~~~~~~~
+
+**type**: ``string`` **default**: ``This value is not valid YAML.``
+
+This message shown if the underlying data is not a valid YAML value.
+
+You can use the following parameters in this message:
+
+===============  ==============================================================
+Parameter        Description
+===============  ==============================================================
+``{{ error }}``  The full error message from the YAML parser
+``{{ line }}``   The line where the YAML syntax error happened
+===============  ==============================================================
+
+.. include:: /reference/constraints/_groups-option.rst.inc
+
+.. include:: /reference/constraints/_payload-option.rst.inc
+
+.. _`YAML`: https://en.wikipedia.org/wiki/YAML