@@ -5,6 +5,10 @@ Validates that a particular field (or fields) in a Doctrine entity is (are)
 unique. This is commonly used, for example, to prevent a new user to register
 using an email address that already exists in the system.
 
+.. versionadded:: 7.1
+
+Any class instance (like DTO) field (or fields) validation against entities persisted in the database was introduced in Symfony 7.1.
+
 .. seealso::
 
 If you want to validate that all the elements of the collection are unique
@@ -162,6 +166,7 @@ the current class instance. However, in some cases, such as when using Doctrine
 inheritance mapping, you need to execute the query in a different repository.
 Use this option to define the fully-qualified class name (FQCN) of the Doctrine
 entity associated with the repository you want to use.
+Another case is when the object being validated is not an entity.
 
 ``errorPath``
 ~~~~~~~~~~~~~
@@ -274,6 +279,125 @@ each with a single field.
 
 .. include:: /reference/constraints/_groups-option.rst.inc
 
+If object being validated field name(s) do not match the one(s) from the entity,
+use key-value mapping; Where ``key`` is the name of the field in the object being
+validated and ``value`` is the name of the field in the entity.
+Field name(s) mapping only applies when the object being validated is not an entity.
+
+``identifierFieldNames``
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+**type**: ``array`` | ``string`` [:ref:`default option <validation-default-option>`]
+
+Use it only when the object being validated is not an entity and you need to update an
+entity with it.
+This option is the identifier field name that is the ``primary key`` or the identifier
+field names that are ``composite keys`` in the entity class set by the `entityClass`_
+option.
+If set, it won’t trigger a uniqueness constraint violation when the only not unique
+entity identifier(s) value(s) will be matching corresponding value(s) from the
+object being validated.
+If object being validated field name(s) do not match the one(s) from the entity,
+use key-value mapping; Where ``key`` is the name of the field in the object being
+validated and ``value`` is the name of the field in the entity.
+
+Consider this example:
+
+.. configuration-block::
+
+.. code-block:: php-attributes
+
+// src/Entity/User.php
+namespace App\Entity;
+
+use Doctrine\ORM\Mapping as ORM;
+
+#[ORM\Entity]
+class User
+{
+#[ORM\Column(type: 'string')]
+public string $id;
+
+#[ORM\Column(type: 'string')]
+public string $username;
+}
+
+// src/Message/UpdateEmployeeProfile.php
+namespace App\Message;
+
+use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;
+
+#[UniqueEntity(
+fields: ['name' => 'username'],
+entityClass: 'App\Entity\User',
+identifierFieldNames: ['uid' => 'id'],
+)]
+class UpdateEmployeeProfile
+{
+public function __construct(public string $uid, public string $name)
+{
+}
+}
+
+ .. code-block:: yaml
+
+# config/validator/validation.yaml
+App\Message\UpdateEmployeeProfile:
+constraints:
+- Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity:
+fields: {name: username}
+entityClass: 'App\Entity\User'
+identifierFieldNames: {uid: id}
+
+ .. 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\Message\UpdateEmployeeProfile">
+<constraint name="Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity">
+<option name="fields">
+<value key="name" >username</value>
+</option>
+<option name="entityClass">App\Entity\User</option>
+<option name="identifierFieldNames">
+<value key="uid" >id</value>
+</option>
+</constraint>
+</class>
+
+</constraint-mapping>
+
+ .. code-block:: php
+
+// src/Message/UpdateEmployeeProfile.php
+namespace App\Message;
+
+use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;
+use Symfony\Component\Validator\Mapping\ClassMetadata;
+
+class UpdateEmployeeProfile
+{
+public string $uid;
+public string $name;
+
+public static function loadValidatorMetadata(ClassMetadata $metadata)
+{
+$metadata->addConstraint(new UniqueEntity([
+'fields' => ['name' => 'username'],
+'entityClass' => 'App\Entity\User',
+'identifierFieldNames' => ['uid' => 'id'],
+]));
+}
+}
+
+.. versionadded:: 7.1
+
+The option was introduced in Symfony 7.1.
+
 ``ignoreNull``
 ~~~~~~~~~~~~~~