adding ttl for documents

DependencyInjection/Configuration.php

@@ -299,6 +299,7 @@ class Configuration implements ConfigurationInterface
                 ->append($this->getParentNode())
                 ->append($this->getAllNode())
                 ->append($this->getTimestampNode())
+                ->append($this->getTtlNode())
             ->end()
         ;
 
@@ -669,4 +670,24 @@ class Configuration implements ConfigurationInterface
 
         return $node;
     }
+    
+    /**
+     * Returns the array node used for "_ttl"
+     */
+    protected function getTtlNode()
+    {
+        $builder = new TreeBuilder();
+        $node = $builder->root('_ttl');
+
+        $node
+            ->children()
+            ->scalarNode('enabled')->defaultValue(true)->end()
+            ->scalarNode('default')->end()
+            ->scalarNode('store')->end()
+            ->scalarNode('index')->end()
+            ->end()
+        ;
+
+        return $node;
+    }    
 }

DependencyInjection/FOSElasticaExtension.php

@@ -249,6 +249,9 @@ class FOSElasticaExtension extends Extension
             if (isset($type['_timestamp'])) {
                 $this->indexConfigs[$indexName]['config']['mappings'][$name]['_timestamp'] = $type['_timestamp'];
             }
+            if (isset($type['_ttl'])) {
+                $this->indexConfigs[$indexName]['config']['mappings'][$name]['_ttl'] = $type['_ttl'];
+            }
             if (!empty($type['dynamic_templates'])) {
                 $this->indexConfigs[$indexName]['config']['mappings'][$name]['dynamic_templates'] = array();
                 foreach ($type['dynamic_templates'] as $templateName => $templateData) {