Fixed #22030 -- Don't assume that all fields have a swappable_setting attribute.

2 files changed, 22 insertions, 1 deletions

diff --git a/django/db/migrations/autodetector.py b/django/db/migrations/autodetector.py
index 2b8759b29a..868d2bdc0f 100644
--- a/django/db/migrations/autodetector.py
+++ b/django/db/migrations/autodetector.py
@@ -233,7 +233,8 @@ class MigrationAutodetector(object):
                         field=field,
                     )
                 )
-                swappable_setting = new_apps.get_model(app_label, model_name)._meta.get_field_by_name(field_name)[0].swappable_setting
+                new_field = new_apps.get_model(app_label, model_name)._meta.get_field_by_name(field_name)[0]
+                swappable_setting = getattr(new_field, 'swappable_setting', None)
                 if swappable_setting is not None:
                     self.add_swappable_dependency(app_label, swappable_setting)
         # Old fields
diff --git a/tests/migrations/test_autodetector.py b/tests/migrations/test_autodetector.py
index dca971dd8e..5c1600ec3d 100644
--- a/tests/migrations/test_autodetector.py
+++ b/tests/migrations/test_autodetector.py
@@ -16,6 +16,7 @@ class AutodetectorTests(TestCase):
     author_name = ModelState("testapp", "Author", [("id", models.AutoField(primary_key=True)), ("name", models.CharField(max_length=200))])
     author_name_longer = ModelState("testapp", "Author", [("id", models.AutoField(primary_key=True)), ("name", models.CharField(max_length=400))])
     author_name_renamed = ModelState("testapp", "Author", [("id", models.AutoField(primary_key=True)), ("names", models.CharField(max_length=200))])
+    author_name_default = ModelState("testapp", "Author", [("id", models.AutoField(primary_key=True)), ("name", models.CharField(max_length=200, default='Ada Lovelace'))])
     author_with_book = ModelState("testapp", "Author", [("id", models.AutoField(primary_key=True)), ("name", models.CharField(max_length=200)), ("book", models.ForeignKey("otherapp.Book"))])
     author_with_publisher = ModelState("testapp", "Author", [("id", models.AutoField(primary_key=True)), ("name", models.CharField(max_length=200)), ("publisher", models.ForeignKey("testapp.Publisher"))])
     author_with_custom_user = ModelState("testapp", "Author", [("id", models.AutoField(primary_key=True)), ("name", models.CharField(max_length=200)), ("user", models.ForeignKey("thirdapp.CustomUser"))])
@@ -369,3 +370,22 @@ class AutodetectorTests(TestCase):
         # Check the dependency is correct
         migration = changes['testapp'][0]
         self.assertEqual(migration.dependencies, [("__setting__", "AUTH_USER_MODEL")])
+
+    def test_add_field_with_default(self):
+        """
+        Adding a field with a default should work (#22030).
+        """
+        # Make state
+        before = self.make_project_state([self.author_empty])
+        after = self.make_project_state([self.author_name_default])
+        autodetector = MigrationAutodetector(before, after)
+        changes = autodetector._detect_changes()
+        # Right number of migrations?
+        self.assertEqual(len(changes['testapp']), 1)
+        # Right number of actions?
+        migration = changes['testapp'][0]
+        self.assertEqual(len(migration.operations), 1)
+        # Right action?
+        action = migration.operations[0]
+        self.assertEqual(action.__class__.__name__, "AddField")
+        self.assertEqual(action.name, "name")