Use a custom migration operation instead of a RunSQL statement

django_migration_linter/__init__.py

@@ -13,4 +13,4 @@
 # limitations under the License.
 
 from .migration_linter import *  # noqa
-from .constants import *  # noqa
+from .operations import *  # noqa

django_migration_linter/constants.py

@@ -1,4 +0,0 @@
-# Can be used to mark ignored migrations.
-# This is a noop for SQL. Comments would be better.
-# But comments are stripped by RunSQL
-IGNORE_MIGRATION = ("SELECT 'dml-ignore'", )

django_migration_linter/operations.py

@@ -0,0 +1,38 @@
+# Copyright 2018 3YOURMIND GmbH
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+# http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from django.db.migrations.operations.base import Operation
+
+IGNORE_MIGRATION_SQL = "-- dml ignores this migration"
+
+
+class IgnoreMigration(Operation):
+
+    reversible = True
+    # Must be true to be generated through the sqlmigrate command
+    reduces_to_sql = True
+
+    def state_forwards(self, app_label, state):
+        pass
+
+    def database_forwards(
+            self, app_label, schema_editor, from_state, to_state):
+        schema_editor.execute(IGNORE_MIGRATION_SQL)
+
+    def database_backwards(
+            self, app_label, schema_editor, from_state, to_state):
+        schema_editor.execute(IGNORE_MIGRATION_SQL + "(reversed)")
+
+    def describe(self):
+        return "The Django migration linter will ignore this migration"

django_migration_linter/sql_analyser.py

@@ -15,7 +15,9 @@
 import re
 import logging
 
-from django_migration_linter.constants import IGNORE_MIGRATION
+from django_migration_linter.operations import IGNORE_MIGRATION_SQL
+
+IGNORED_MIGRATION = "IGNORED_MIGRATION"
 
 logger = logging.getLogger(__name__)
 
@@ -66,8 +68,8 @@ migration_tests = (
         'fn': has_default,
         'err_msg': ''
     }, {
-        'code': 'IGNORED_MIGRATION',
-        'fn': lambda sql, **kw: re.search(IGNORE_MIGRATION[0], sql),
+        'code': IGNORED_MIGRATION,
+        'fn': lambda sql, **kw: re.search(IGNORE_MIGRATION_SQL, sql),
         'err_msg': '',
     }
 )
@@ -79,7 +81,7 @@ def analyse_sql_statements(sql_statements):
     for statement in sql_statements:
         for test in migration_tests:
             if test['fn'](statement, errors=errors):
-                if test['code'] == 'IGNORED_MIGRATION':
+                if test['code'] == IGNORED_MIGRATION:
                     logger.info(
                         'Testing {0} -- IGNORING MIGRATION'.format(statement)
                     )