Merge pull request #79 from HusseinKabbout/master

Check database connection on jointables to make sure that the layer is a postgres layer

src/config_generator/qgs_reader.py

@@ -558,7 +558,7 @@ def __lookup_attribute_data_types(self, meta):
                 constraints = OrderedDict()
 
                 joinfield = fields.get(attr).get('joinfield')
-                if joinfield:
+                if joinfield and meta['jointables'][joinfield['table']]['database'] is not None:
                     jointable = joinfield['table']
                     jointablemeta = meta['jointables'][jointable]
                     if jointable not in joindbs: