Fixed #23728 -- Added the --exit option to makemigrations.

If no changes that need migrations are found, `makemigrations --exit`
exits with error code 1.

AUTHORS

@@ -649,6 +649,7 @@ answer newbie questions, and generally made Django that much better:
     Thomas Stromberg <tstromberg@google.com>
     tibimicu@gmx.net
     Tim Graham <timograham@gmail.com>
+    Tim Heap <tim@timheap.me>
     Tim Saylor <tim.saylor@gmail.com>
     Tobias McNulty <http://www.caktusgroup.com/blog>
     tobias@neuyork.de

django/core/management/commands/makemigrations.py

@@ -30,6 +30,8 @@ class Command(BaseCommand):
             help='Tells Django to NOT prompt the user for input of any kind.')
         parser.add_argument('-n', '--name', action='store', dest='name', default=None,
             help="Use this name for migration file(s).")
+        parser.add_argument('-e', '--exit', action='store_true', dest='exit_code', default=False,
+            help='Exit with error code 1 if no changes needing migrations are found.')
 
     def handle(self, *app_labels, **options):
 
@@ -39,6 +41,7 @@ class Command(BaseCommand):
         self.merge = options.get('merge', False)
         self.empty = options.get('empty', False)
         self.migration_name = options.get('name', None)
+        self.exit_code = options.get('exit_code', False)
 
         # Make sure the app they asked for exists
         app_labels = set(app_labels)
@@ -120,14 +123,19 @@ class Command(BaseCommand):
             migration_name=self.migration_name,
         )
 
+        if not changes:
             # No changes? Tell them.
-        if not changes and self.verbosity >= 1:
+            if self.verbosity >= 1:
                 if len(app_labels) == 1:
                     self.stdout.write("No changes detected in app '%s'" % app_labels.pop())
                 elif len(app_labels) > 1:
                     self.stdout.write("No changes detected in apps '%s'" % ("', '".join(app_labels)))
                 else:
                     self.stdout.write("No changes detected")
+
+            if self.exit_code:
+                sys.exit(1)
+            else:
                 return
 
         self.write_migration_files(changes)

docs/ref/django-admin.txt

@@ -719,6 +719,14 @@ a merge.
 The ``--name`` option allows you to give the migration(s) a custom name instead
 of a generated one.
 
+.. django-admin-option:: --exit, -e
+
+.. versionadded:: 1.8
+
+The ``--exit`` option will cause ``makemigrations`` to exit with error code 1
+when no migration are created (or would have been created, if combined with
+``--dry-run``).
+
 migrate [<app_label> [<migrationname>]]
 ---------------------------------------
 

docs/releases/1.8.txt

@@ -333,6 +333,9 @@ Management Commands
   :setting:`FIXTURE_DIRS` contains duplicates or a default fixture directory
   path (``app_name/fixtures``), an exception is raised.
 
+* :djadmin:`makemigrations` now supports an :djadminopt:`--exit` option to
+  exit with an error code if no migrations are created.
+
 Middleware
 ^^^^^^^^^^
 

tests/migrations/test_commands.py

@@ -543,6 +543,18 @@ class MakeMigrationsTests(MigrationTestBase):
         self.assertIn("dependencies=[\n('migrations','0001_%s'),\n]" % migration_name_0001, content)
         self.assertIn("operations=[\n]", content)
 
+    def test_makemigrations_exit(self):
+        """
+        makemigrations --exit should exit with sys.exit(1) when there are no
+        changes to an app.
+        """
+        with self.settings(MIGRATION_MODULES={"migrations": self.migration_pkg}):
+            call_command("makemigrations", "--exit", "migrations", verbosity=0)
+
+        with self.settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_no_changes"}):
+            with self.assertRaises(SystemExit):
+                call_command("makemigrations", "--exit", "migrations", verbosity=0)
+
 
 class SquashMigrationsTest(MigrationTestBase):
     """