Added Database.does_table_exist method

CHANGELOG.md

@@ -5,6 +5,7 @@ Unreleased
 ----------
 - Include alias and materialized fields in queryset results
 - Check for database existence, to allow delayed creation
+- Added `Database.does_table_exist` method
 
 v1.0.1
 ------

src/infi/clickhouse_orm/database.py

@@ -134,6 +134,15 @@ class Database(object):
             raise DatabaseException("You can't drop system table")
         self._send(model_class.drop_table_sql(self))
 
+    def does_table_exist(self, model_class):
+        '''
+        Checks whether a table for the given model class already exists.
+        Note that this only checks for existence of a table with the expected name.
+        '''
+        sql = "SELECT count() FROM system.tables WHERE database = '%s' AND name = '%s'"
+        r = self._send(sql % (self.db_name, model_class.table_name()))
+        return r.text.strip() == '1'
+
     def insert(self, model_instances, batch_size=1000):
         '''
         Insert records into the database.

tests/test_database.py

@@ -179,3 +179,8 @@ class DatabaseTestCase(TestCaseWithData):
         instance = Model1.objects_in(self.database)[0]
         self.assertEquals(instance.to_dict(), dict(system='s', readonly='r'))
 
+    def test_does_table_exist(self):
+        class Person2(Person):
+            pass
+        self.assertTrue(self.database.does_table_exist(Person))
+        self.assertFalse(self.database.does_table_exist(Person2))