[Validator][Doctrine] Add docs for automatic validation

doctrine.rst

@@ -412,6 +412,72 @@ Take a look at the previous example in more detail:
 Whether you're creating or updating objects, the workflow is always the same: Doctrine
 is smart enough to know if it should INSERT or UPDATE your entity.
 
+Validating Objects
+------------------
+
+:doc:`The Symfony validator </validation>` reuse Doctrine metadata
+to perform some basic validation tasks::
+
+ // src/Controller/ProductController.php
+ namespace App\Controller;
+
+ // ...
+ use Symfony\Component\HttpFoundation\Response;
+ use Symfony\Component\Validator\Validator\ValidatorInterface;
+
+ use App\Entity\Product;
+
+ class ProductController extends AbstractController
+ {
+ /**
+ * @Route("/product", name="product")
+ */
+ public function index(ValidatorInterface $validator)
+ {
+ $product = new Product();
+ $product->setName(null); // The column in database isn't nullable
+ $product->setPrice('1999'); // Type mismatch, an integer is expected
+
+ // ...
+
+ $errors = $validator->validate($product);
+ if (count($errors) > 0) {
+ return new Response((string) $errors, 400);
+ }
+
+ // Will not be reached in this example
+ $entityManager = $this->getDoctrine()->getManager();
+ $entityManager->persist($product);
+ $entityManager->flush();
+
+ return new Response('Saved new product with id '.$product->getId());
+ }
+ }
+
+The following table summaries the mapping between Doctrine metadata and
+the corresponding validation constraints:
+
++--------------------+-----------------------------------------------------------+-------------------------------------------------------------------------+
+| Doctrine attribute | Validation constraint | Notes |
++====================+===========================================================+=========================================================================+
+| ``nullable=true`` | :doc:`NotNull </reference/constraints/NotNull>` | Relies on :doc:`the PropertyInfo component </components/property_info>` |
++--------------------+-----------------------------------------------------------+-------------------------------------------------------------------------+
+| ``type`` | :doc:`Type </reference/constraints/Type>` | Relies on :doc:`the PropertyInfo component </components/property_info>` |
++--------------------+-----------------------------------------------------------+-------------------------------------------------------------------------+
+| ``unique=true`` | :doc:`UniqueEntity </reference/constraints/UniqueEntity>` | |
++--------------------+-----------------------------------------------------------+-------------------------------------------------------------------------+
+| ``length`` | :doc:`Length </reference/constraints/Length>` | |
++--------------------+-----------------------------------------------------------+-------------------------------------------------------------------------+
+
+Because :doc:`the Form component </forms>` as well as `API Platform`_
+internally use the Validator Component, all your forms
+and web APIs will also automatically benefit from these default constraints.
+
+.. tip::
+
+ Don't forget to add :doc:`more precise validation constraints </reference/constraints>`
+ to ensure that data provided by the user is correct.
+
 Fetching Objects from the Database
 ----------------------------------
 
@@ -812,3 +878,4 @@ Learn more
 .. _`ParamConverter`: http://symfony.com/doc/current/bundles/SensioFrameworkExtraBundle/annotations/converters.html
 .. _`limit of 767 bytes for the index key prefix`: https://dev.mysql.com/doc/refman/5.6/en/innodb-restrictions.html
 .. _`Doctrine screencast series`: https://symfonycasts.com/screencast/symfony-doctrine
+.. _`API Platform`: https://api-platform.com/docs/core/validation/