feature #1364 Display an error message when an entity doesn't define …

…a __toString() method (javiereguiluz)

This PR was squashed before being merged into the master branch (closes #1364).

Discussion
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Display an error message when an entity doesn't define a __toString() method

Sadly, it's common to forget adding the `__toString()` method in entities used as part of Doctrine associations. We now display a useful error message in those cases:

![tostring_error_message](https://cloud.githubusercontent.com/assets/73419/20029565/7340bad4-a34f-11e6-9614-b4fd55c7820a.png)

Commits
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08d08c8 Display an error message when an entity doesn't define a __toString() method

Configuration/ConfigManager.php

@@ -191,6 +191,7 @@ private function doProcessConfig($backendConfig)
             new ViewConfigPass(),
             new TemplateConfigPass($this->container->getParameter('kernel.root_dir').'/Resources/views'),
             new DefaultConfigPass(),
+            new ValidationConfigPass(),
         );
 
         foreach ($configPasses as $configPass) {

Configuration/ValidationConfigPass.php

@@ -0,0 +1,63 @@
+<?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\Configuration;
+
+/**
+ * Performs the last validations on the processed backend configuration before
+ * executing the application.
+ *
+ * @author Javier Eguiluz <javier.eguiluz@gmail.com>
+ */
+class ValidationConfigPass implements ConfigPassInterface
+{
+    public function process(array $backendConfig)
+    {
+        $this->validateToStringMethod($backendConfig);
+
+        return $backendConfig;
+    }
+
+    /**
+     * It checks that the __toString() method is defined in the entity classes
+     * that need it. This avoids the usual error "Object of class ... could not
+     * be converted to string".
+     *
+     * @param array $backendConfig
+     */
+    private function validateToStringMethod(array $backendConfig)
+    {
+        foreach ($backendConfig['entities'] as $entityName => $entityConfig) {
+            foreach (array('list', 'search', 'show') as $view) {
+                foreach ($entityConfig[$view]['fields'] as $fieldName => $fieldConfig) {
+                    // Doctrine associations that don't define a custom template must define a __toString() method
+                    $fieldUsesDefaultTemplate = '@EasyAdmin/default/field_association.html.twig' === $fieldConfig['template'];
+                    if ('association' === $fieldConfig['dataType'] && $fieldUsesDefaultTemplate) {
+                        if (!method_exists($fieldConfig['targetEntity'], '__toString')) {
+                            throw new \InvalidArgumentException(sprintf('The "%s" class must define a "__toString()" method because it is used as the "%s" field in the "%s" view of the "%s" entity.', $fieldConfig['targetEntity'], $fieldName, $view, $entityName));
+                        }
+                    }
+                }
+            }
+
+            foreach (array('edit', 'new') as $view) {
+                foreach ($entityConfig[$view]['fields'] as $fieldName => $fieldConfig) {
+                    // fields used in autocomplete form types must define a __toString() method
+                    if ('easyadmin_autocomplete' === $fieldConfig['fieldType']) {
+                        if (!method_exists($fieldConfig['targetEntity'], '__toString')) {
+                            throw new \InvalidArgumentException(sprintf('The "%s" class must define a "__toString()" method because it is used as the "%s" autocomplete field in the "%s" view of the "%s" entity.', $fieldConfig['targetEntity'], $fieldName, $view, $entityName));
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

Tests/Configuration/fixtures/exceptions/association_without_tostring.yml

@@ -0,0 +1,13 @@
+# TEST
+# the entity classes used in associations must define a __toString() method
+
+# EXCEPTION
+expected_exception:
+    class: InvalidArgumentException
+    message_string: 'The "AppTestBundle\Entity\UnitTests\Exceptions\CategoryWithoutToString" class must define a "__toString()" method because it is used as the "parent" field in the "list" view of the "Category" entity.'
+
+# CONFIGURATION
+easy_admin:
+    entities:
+        Category:
+            class: AppTestBundle\Entity\UnitTests\Exceptions\CategoryWithoutToString

Tests/Configuration/fixtures/exceptions/autocomplete_without_tostring.yml

@@ -0,0 +1,22 @@
+# TEST
+# the entity classes used in autocomplete types must define a __toString() method
+
+# EXCEPTION
+expected_exception:
+    class: InvalidArgumentException
+    message_string: 'The "AppTestBundle\Entity\UnitTests\Exceptions\CategoryWithoutToString" class must define a "__toString()" method because it is used as the "parent" autocomplete field in the "edit" view of the "Category" entity.'
+
+# CONFIGURATION
+easy_admin:
+    entities:
+        Category:
+            class: AppTestBundle\Entity\UnitTests\Exceptions\CategoryWithoutToString
+            # don't include the 'parent' field in the 'list' and 'show' views to avoid
+            # exceptions that would prevent to test the exception thrown in the 'form' view
+            list:
+                fields: ['id']
+            show:
+                fields: ['id']
+            form:
+                fields:
+                    - { property: parent, type: easyadmin_autocomplete }

Tests/Fixtures/AppTestBundle/Entity/FunctionalTests/Category.php

@@ -66,7 +66,6 @@ public function __construct()
         $this->products = new ArrayCollection();
     }
 
-    /** {@inheritdoc} */
     public function __toString()
     {
         return $this->getName();

Tests/Fixtures/AppTestBundle/Entity/FunctionalTests/Image.php

@@ -45,6 +45,11 @@ class Image
      */
     protected $thumbnail;
 
+    public function __toString()
+    {
+        return 'Image #'.$this->id();
+    }
+
     /**
      * Set the content of the full size image.
      *

Tests/Fixtures/AppTestBundle/Entity/FunctionalTests/Product.php

@@ -403,9 +403,6 @@ public function getId()
         return $this->id;
     }
 
-    /**
-     * {@inheritdoc}
-     */
     public function __toString()
     {
         return $this->getName();

Tests/Fixtures/AppTestBundle/Entity/UnitTests/Exceptions/CategoryWithoutToString.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace AppTestBundle\Entity\UnitTests\Exceptions;
+
+use Doctrine\ORM\Mapping as ORM;
+
+/**
+ * This entity doesn't contain a __toString() method to force an exception
+ * in some tests.
+ *
+ * @ORM\Entity
+ */
+class CategoryWithoutToString
+{
+    /**
+     * @ORM\Column(name="id", type="integer")
+     * @ORM\Id
+     * @ORM\GeneratedValue(strategy="AUTO")
+     */
+    protected $id;
+
+    /**
+     * @ORM\OneToOne(targetEntity="CategoryWithoutToString")
+     * @ORM\JoinColumn(name="parent_id", referencedColumnName="id", nullable=true)
+     */
+    protected $parent;
+
+    public function getId()
+    {
+        return $this->id;
+    }
+
+    public function setParent($parent)
+    {
+        $this->parent = $parent;
+    }
+
+    public function getParent()
+    {
+        return $this->parent;
+    }
+}