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Fixed #24435 -- Prevented m2m field removal and addition in migrations when changing blank 

Thanks Mark Tranchant for the report an Tim Graham for the test and
review.
This commit is contained in:
Markus Holtermann 2015-03-04 09:36:53 +01:00
parent 70123cf084
commit a9e29fae10
2 changed files with 25 additions and 2 deletions
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13
django/db/migrations/autodetector.py
View File

@ -848,8 +848,16 @@ class MigrationAutodetector(object):
old_field_dec = self.deep_deconstruct(old_field)
new_field_dec = self.deep_deconstruct(new_field)
if old_field_dec != new_field_dec:
if (not isinstance(old_field, models.ManyToManyField) and
not isinstance(new_field, models.ManyToManyField)):
both_m2m = (
isinstance(old_field, models.ManyToManyField) and
isinstance(new_field, models.ManyToManyField)
)
neither_m2m = (
not isinstance(old_field, models.ManyToManyField) and
not isinstance(new_field, models.ManyToManyField)
)
if both_m2m or neither_m2m:
# Either both fields are m2m or neither is
preserve_default = True
if (old_field.null and not new_field.null and not new_field.has_default() and
not isinstance(new_field, models.ManyToManyField)):
@ -870,6 +878,7 @@ class MigrationAutodetector(object):
)
)
else:
# We cannot alter between m2m and concrete fields
self._generate_removed_field(app_label, model_name, field_name)
self._generate_added_field(app_label, model_name, field_name)

14
tests/migrations/test_autodetector.py
View File

@ -127,6 +127,10 @@ class AutodetectorTests(TestCase):
("id", models.AutoField(primary_key=True)),
("publishers", models.ManyToManyField("testapp.Publisher")),
])
author_with_m2m_blank = ModelState("testapp", "Author", [
("id", models.AutoField(primary_key=True)),
("publishers", models.ManyToManyField("testapp.Publisher", blank=True)),
])
author_with_m2m_through = ModelState("testapp", "Author", [
("id", models.AutoField(primary_key=True)),
("publishers", models.ManyToManyField("testapp.Publisher", through="testapp.Contract")),
@ -1263,6 +1267,16 @@ class AutodetectorTests(TestCase):
self.assertOperationTypes(changes, 'testapp', 0, ["AddField"])
self.assertOperationAttributes(changes, 'testapp', 0, 0, name="publishers")
def test_alter_many_to_many(self):
before = self.make_project_state([self.author_with_m2m, self.publisher])
after = self.make_project_state([self.author_with_m2m_blank, self.publisher])
autodetector = MigrationAutodetector(before, after)
changes = autodetector._detect_changes()
# Right number/type of migrations?
self.assertNumberMigrations(changes, 'testapp', 1)
self.assertOperationTypes(changes, 'testapp', 0, ["AlterField"])
self.assertOperationAttributes(changes, 'testapp', 0, 0, name="publishers")
def test_create_with_through_model(self):
"""
Adding a m2m with a through model and the models that use it should be