added path support, see http://www.elasticsearch.org/guide/reference/mapping/id-field/

DependencyInjection/Configuration.php

@@ -281,6 +281,7 @@ class Configuration implements ConfigurationInterface
                         ->end()
                     ->end()
                 ->end()
+                ->append($this->getIdNode())
                 ->append($this->getMappingsNode())
                 ->append($this->getSourceNode())
                 ->append($this->getBoostNode())
@@ -435,6 +436,23 @@ class Configuration implements ConfigurationInterface
         $nestings[$property] = array_merge_recursive($nestings[$property], $this->getNestingsForType($field[$property]));
     }
 
+    /**
+     * Returns the array node used for "_id".
+     */
+    protected function getIdNode()
+    {
+        $builder = new TreeBuilder();
+        $node = $builder->root('_id');
+
+        $node
+            ->children()
+            ->scalarNode('path')->end()
+            ->end()
+        ;
+
+        return $node;
+    }
+
     /**
      * Returns the array node used for "_source".
      */

DependencyInjection/FOSElasticaExtension.php

@@ -197,6 +197,9 @@ class FOSElasticaExtension extends Extension
                 $typeDef->addMethodCall('setSerializer', array(array(new Reference($callbackId), 'serialize')));
             }
             $container->setDefinition($typeId, $typeDef);
+            if (isset($type['_id'])) {
+                $this->indexConfigs[$indexName]['config']['mappings'][$name]['_id'] = $type['_id'];
+            }
             if (isset($type['_source'])) {
                 $this->indexConfigs[$indexName]['config']['mappings'][$name]['_source'] = $type['_source'];
             }