minor compatibility fix in ldap_auth

gluon/contrib/login_methods/ldap_auth.py

@@ -521,17 +521,19 @@ def ldap_auth(server='ldap', port=None,
                 logging.error(
                     'There is no username or email for %s!' % username)
                 raise
-            if not db.can_join():
+            # if old pydal version, assume this is a relational database which can do joins
-                # no joins on NoSQL databases, perform two queries
+            db_can_join = db.can_join() if hasattr(db, 'can_join') else True
-                db_group_search = db(db.auth_membership.user_id == db_user_id)
+            if db_can_join:
-                group_ids = [x.group_id for x in db_group_search.select(
-                    db.auth_membership.group_id, distinct=True)]
-                db_group_search = db(db.auth_group.id == group_ids)
-            else:
                 db_group_search = db(
                     (db.auth_membership.user_id == db_user_id) &
                     (db.auth_user.id == db.auth_membership.user_id) &
                     (db.auth_group.id == db.auth_membership.group_id))
+            else:
+                # no joins on NoSQL databases, perform two queries
+                db_group_search = db(db.auth_membership.user_id == db_user_id)
+                group_ids = [x.group_id for x in db_group_search.select(
+                        db.auth_membership.group_id, distinct=True)]
+                db_group_search = db(db.auth_group.id.belongs(group_ids))
             db_groups_of_the_user = list()
             db_group_id = dict()