[Fixes #223] Migration error 0005_fixup_dynamic_shema_table_names (#224)

* [Fixes #223] Migration error 0005_fixup_dynamic_shema_table_names

importer/migrations/0005_fixup_dynamic_shema_table_names.py

@@ -1,26 +1,23 @@
 from django.db import migrations
 import logging
 from django.db import ProgrammingError
+from django.db import connections
 
 logger = logging.getLogger(__name__)
 
 
 def fixup_table_name(apps, schema_editor):
     try:
-        schema = apps.get_model("dynamic_models", "ModelSchema")
-        for val in schema.objects.all():
-            if val.name != val.db_table_name:
-                val.db_table_name = val.name
-                val.save()
-    except ProgrammingError as e:
         """
-        The dynamic model should exists to apply the above migration.
+        The dynamic model should exists to apply the migration.
         In case it does not exists we can skip it
         """
-        if 'relation "dynamic_models_modelschema" does not exist' in e.args[0]:
-            logging.debug("Dynamic model does not exists yet, skipping")
-            return
-        raise e
+        if 'dynamic_models_modelschema' in schema_editor.connection.introspection.table_names():
+            schema = apps.get_model("dynamic_models", "ModelSchema")
+            for val in schema.objects.all():
+                if val.name != val.db_table_name:
+                    val.db_table_name = val.name
+                    val.save()
     except Exception as e:
         raise e