update routing

Resources/config/routing/base_application.xml

@@ -8,7 +8,7 @@
         <default key="_controller">Sonata\BaseApplicationBundle:Core:dashboard</default>
     </route>
 
-    <route id="sonata_base_application_retrieve_form_element" pattern="/core/:code/get-form-field-element/:element_id">
+    <route id="sonata_base_application_retrieve_form_element" pattern="/core/{code}/get-form-field-element/{element_id}">
         <default key="_controller">Sonata\BaseApplicationBundle:Core:retrieveFormFieldElement</default>
     </route>