erp5_credential: Fix external validator to check login availability in ERP5JS

bt5/erp5_credential/SkinTemplateItem/portal_skins/erp5_credential/CredentialRequest_checkLoginAvailability.py

@@ -17,7 +17,7 @@ if value:
 def getRealContext():
   if not REQUEST:
     return context
-  object_path = REQUEST.get("object_path")
+  object_path = REQUEST.get("object_path") or REQUEST.get("field_your_object_path") 
   return portal.restrictedTraverse(object_path)
 
 #Allow user to create a request with it's username

bt5/erp5_credential/SkinTemplateItem/portal_skins/erp5_credential/CredentialRequest_view.xml

@@ -123,6 +123,7 @@
                         <string>my_start_date</string>
                         <string>my_stop_date</string>
                         <string>my_url_string</string>
+                        <string>your_object_path</string>
                       </list>
                     </value>
                 </item>