feature #1397 Display a proper error message when a database item can…

…not be removed (javiereguiluz)

This PR was merged into the master branch.

Discussion
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Display a proper error message when a database item cannot be removed

This fixes #747.

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When you try to remove an entity which doesn't have a `cascade: remove` option, Symfony/Doctrine display the following error message in production:

![error_before](https://cloud.githubusercontent.com/assets/73419/20457012/b296a5a8-ae81-11e6-8f98-9b16808676d7.png)

Now, thanks to this new exception, we can display a human-friendly message for this common error:

![error_after](https://cloud.githubusercontent.com/assets/73419/20457018/c0fe9736-ae81-11e6-91d1-384d0497c746.png)

Commits
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570f6a8 Display a proper error message when a database item cannot be removed

Controller/AdminController.php

@@ -11,9 +11,11 @@
 
 namespace JavierEguiluz\Bundle\EasyAdminBundle\Controller;
 
+use Doctrine\DBAL\Exception\ForeignKeyConstraintViolationException;
 use Doctrine\ORM\EntityManager;
 use Doctrine\ORM\QueryBuilder;
 use JavierEguiluz\Bundle\EasyAdminBundle\Event\EasyAdminEvents;
+use JavierEguiluz\Bundle\EasyAdminBundle\Exception\EntityRemoveException;
 use JavierEguiluz\Bundle\EasyAdminBundle\Exception\ForbiddenActionException;
 use JavierEguiluz\Bundle\EasyAdminBundle\Exception\NoEntitiesConfiguredException;
 use JavierEguiluz\Bundle\EasyAdminBundle\Exception\UndefinedEntityException;
@@ -332,8 +334,12 @@ protected function deleteAction()
 
             $this->executeDynamicMethod('preRemove<EntityName>Entity', array($entity));
 
-            $this->em->remove($entity);
-            $this->em->flush();
+            try {
+                $this->em->remove($entity);
+                $this->em->flush();
+            } catch (ForeignKeyConstraintViolationException $e) {
+                throw new EntityRemoveException(array('entity' => $this->entity['name']));
+            }
 
             $this->dispatch(EasyAdminEvents::POST_REMOVE, array('entity' => $entity));
         }

Exception/EntityRemoveException.php

@@ -0,0 +1,26 @@
+<?php
+
+/*
+ * This file is part of the EasyAdminBundle.
+ *
+ * (c) Javier Eguiluz <javier.eguiluz@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JavierEguiluz\Bundle\EasyAdminBundle\Exception;
+
+/**
+ * @author Javier Eguiluz <javier.eguiluz@gmail.com>
+ */
+class EntityRemoveException extends BaseException
+{
+    public function __construct(array $parameters = array())
+    {
+        $errorMessage = sprintf('You can\'t delete this "%s" item because other items depend on it in the database.', $parameters['entity']);
+        $proposedSolution = "Don't delete this item or change the database configuration to allow deleting it.";
+
+        parent::__construct($errorMessage, $proposedSolution, 404);
+    }
+}