Fix Decimal database defaults

Author: timgraham

django_snowflake/features.py

@@ -29,6 +29,9 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     has_json_object_function = False
     indexes_foreign_keys = False
     nulls_order_largest = True
+    # At least for DecimalField, Snowflake errors with "Default value data type
+    # does not match data type for column" if the default isn't serialized.
+    requires_literal_defaults = True
     supported_explain_formats = {'JSON', 'TABULAR', 'TEXT'}
     supports_comments = True
     supports_comments_inline = True

django_snowflake/schema.py

@@ -169,10 +169,13 @@ def _column_generated_sql(self, field):
 
     def quote_value(self, value):
         if isinstance(value, str):
-            return "'%s'" % value.replace("'", "\\'")
+            return "'%s'" % value.replace("'", "\\'").replace("%", "%%")
         else:
             return str(value)
 
+    def prepare_default(self, value):
+        return self.quote_value(value)
+
     def skip_default_on_alter(self, field):
         # Snowflake: Unsupported feature 'Alter Column Set Default'.
         return True