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Code Issues 32 Releases Wiki Activity

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

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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
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@@ -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)