Merge branch '2.8' into 3.4

* 2.8:
  Simplify Apache config with FallbackResource
  Made the code of a validation example more robust

Author: javiereguiluz

setup/web_server_configuration.rst

@@ -79,12 +79,7 @@ and increase web server performance:
             Order Allow,Deny
             Allow from All
 
-            <IfModule mod_rewrite.c>
-                Options -MultiViews
-                RewriteEngine On
-                RewriteCond %{REQUEST_FILENAME} !-f
-                RewriteRule ^(.*)$ app.php [QSA,L]
-            </IfModule>
+            FallbackResource /app.php
         </Directory>
 
         # uncomment the following lines if you install assets as symlinks
@@ -93,13 +88,11 @@ and increase web server performance:
         #     Options FollowSymlinks
         # </Directory>
 
-        # optionally disable the RewriteEngine for the asset directories
-        # which will allow apache to simply reply with a 404 when files are
-        # not found instead of passing the request into the full symfony stack
+        # optionally disable the fallback resource for the asset directories
+        # which will allow Apache to return a 404 error when files are
+        # not found instead of passing the request to Symfony
         <Directory /var/www/project/web/bundles>
-            <IfModule mod_rewrite.c>
-                RewriteEngine Off
-            </IfModule>
+            FallbackResource disabled
         </Directory>
         ErrorLog /var/log/apache2/project_error.log
         CustomLog /var/log/apache2/project_access.log combined

validation/custom_constraint.rst

@@ -59,11 +59,22 @@ The validator class is also simple, and only has one required method ``validate(
 
     use Symfony\Component\Validator\Constraint;
     use Symfony\Component\Validator\ConstraintValidator;
+    use Symfony\Component\Validator\Exception\UnexpectedTypeException;
 
     class ContainsAlphanumericValidator extends ConstraintValidator
     {
         public function validate($value, Constraint $constraint)
         {
+            // custom constraints should ignore null and empty values to allow
+            // other constraints (NotBlank, NotNull, etc.) take care of that
+            if (null === $value || '' === $value) {
+                return;
+            }
+
+            if (!is_string($value)) {
+                throw new UnexpectedTypeException($value, 'string');
+            }
+
             if (!preg_match('/^[a-zA-Z0-9]+$/', $value, $matches)) {
                 $this->context->buildViolation($constraint->message)
                     ->setParameter('{{ string }}', $value)