From 5455d6d9b47d130f2717fd496a1561d3307853cb Mon Sep 17 00:00:00 2001
From: M1ha <work_shvein_mihail@mail.ru>
Date: Thu, 22 Nov 2018 16:59:39 +0500
Subject: [PATCH] Fixed bug in migrations, if migrations directory doesn't
 exist in module

---
 src/django_clickhouse/migrations.py | 27 ++++++++++++++-------------
 src/django_clickhouse/utils.py      | 14 ++++++++++++--
 2 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/src/django_clickhouse/migrations.py b/src/django_clickhouse/migrations.py
index e9a274f..1f2dbe4 100644
--- a/src/django_clickhouse/migrations.py
+++ b/src/django_clickhouse/migrations.py
@@ -10,7 +10,7 @@ from django.db import DEFAULT_DB_ALIAS as DJANGO_DEFAULT_DB_ALIAS
 from infi.clickhouse_orm.migrations import MigrationHistory
 from infi.clickhouse_orm.utils import import_submodules
 
-from django_clickhouse.utils import lazy_class_import
+from django_clickhouse.utils import lazy_class_import, module_exists
 from .configuration import config
 from .database import connections
 
@@ -48,22 +48,23 @@ def migrate_app(app_label, db_alias, up_to=9999):
     """
     db = connections[db_alias]
     migrations_package = "%s.%s" % (app_label, config.MIGRATIONS_PACKAGE)
-    
-    applied_migrations = db._get_applied_migrations(migrations_package)
-    modules = import_submodules(migrations_package)
 
-    unapplied_migrations = set(modules.keys()) - applied_migrations
+    if module_exists(migrations_package):
+        applied_migrations = db._get_applied_migrations(migrations_package)
+        modules = import_submodules(migrations_package)
 
-    for name in sorted(unapplied_migrations):
-        migration = modules[name].Migration()
-        migration.apply(db_alias)
+        unapplied_migrations = set(modules.keys()) - applied_migrations
 
-        db.insert([
-            MigrationHistory(package_name=migrations_package, module_name=name, applied=datetime.date.today())
-        ])
+        for name in sorted(unapplied_migrations):
+            migration = modules[name].Migration()
+            migration.apply(db_alias)
 
-        if int(name[:4]) >= up_to:
-            break
+            db.insert([
+                MigrationHistory(package_name=migrations_package, module_name=name, applied=datetime.date.today())
+            ])
+
+            if int(name[:4]) >= up_to:
+                break
 
 
 @receiver(post_migrate)
diff --git a/src/django_clickhouse/utils.py b/src/django_clickhouse/utils.py
index 8710fc7..93077ad 100644
--- a/src/django_clickhouse/utils.py
+++ b/src/django_clickhouse/utils.py
@@ -4,8 +4,7 @@ from typing import Union, Any, Optional, TypeVar, Set
 import pytz
 import six
 from importlib import import_module
-
-from infi.clickhouse_orm.database import Database
+from importlib.util import find_spec
 
 from .database import connections
 
@@ -53,6 +52,17 @@ def format_datetime(dt, timezone_offset=0, day_end=False, db_alias=None):
     return server_dt.strftime("%Y-%m-%d %H:%M:%S")
 
 
+def module_exists(module_name):  # type: (str) -> bool
+    """
+    Checks if moudle exists
+    :param module_name: Dot-separated module name
+    :return: Boolean
+    """
+    # Python 3.4+
+    spam_spec = find_spec(module_name)
+    return spam_spec is not None
+
+
 def lazy_class_import(obj):  # type: (Union[str, Any]) -> Any
     """
     If string is given, imports object by given module path.