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Code Issues 32 Releases Wiki Activity

Fixed #18823 -- Ensured m2m.clear() works when using through+to_field

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There was a potential data-loss issue involved -- when clearing
instance's m2m assignments it was possible some other instance's
m2m data was deleted instead.

This commit also improved None handling for to_field cases.
This commit is contained in:
Anssi Kääriäinen
2012-10-28 16:47:07 +02:00
parent 98032f67c7
commit 611c4d6f1c
3 changed files with 128 additions and 15 deletions
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45
django/db/models/fields/related.py
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@@ -573,9 +573,31 @@ def create_many_related_manager(superclass, rel):
self.reverse = reverse
self.through = through
self.prefetch_cache_name = prefetch_cache_name
self._pk_val = self.instance.pk
if self._pk_val is None:
raise ValueError("%r instance needs to have a primary key value before a many-to-many relationship can be used." % instance.__class__.__name__)
self._fk_val = self._get_fk_val(instance, source_field_name)
if self._fk_val is None:
raise ValueError('"%r" needs to have a value for field "%s" before '
'this many-to-many relationship can be used.' %
(instance, source_field_name))
# Even if this relation is not to pk, we require still pk value.
# The wish is that the instance has been already saved to DB,
# although having a pk value isn't a guarantee of that.
if instance.pk is None:
raise ValueError("%r instance needs to have a primary key value before "
"a many-to-many relationship can be used." %
instance.__class__.__name__)
def _get_fk_val(self, obj, field_name):
"""
Returns the correct value for this relationship's foreign key. This
might be something else than pk value when to_field is used.
"""
fk = self.through._meta.get_field(field_name)
if fk.rel.field_name and fk.rel.field_name != fk.rel.to._meta.pk.attname:
attname = fk.rel.get_related_field().get_attname()
return fk.get_prep_lookup('exact', getattr(obj, attname))
else:
return obj.pk
def get_query_set(self):
try:
@@ -677,7 +699,11 @@ def create_many_related_manager(superclass, rel):
if not router.allow_relation(obj, self.instance):
raise ValueError('Cannot add "%r": instance is on database "%s", value is on database "%s"' %
(obj, self.instance._state.db, obj._state.db))
new_ids.add(obj.pk)
fk_val = self._get_fk_val(obj, target_field_name)
if fk_val is None:
raise ValueError('Cannot add "%r": the value for field "%s" is None' %
(obj, target_field_name))
new_ids.add(self._get_fk_val(obj, target_field_name))
elif isinstance(obj, Model):
raise TypeError("'%s' instance expected, got %r" % (self.model._meta.object_name, obj))
else:
@@ -685,7 +711,7 @@ def create_many_related_manager(superclass, rel):
db = router.db_for_write(self.through, instance=self.instance)
vals = self.through._default_manager.using(db).values_list(target_field_name, flat=True)
vals = vals.filter(**{
source_field_name: self._pk_val,
source_field_name: self._fk_val,
'%s__in' % target_field_name: new_ids,
})
new_ids = new_ids - set(vals)
@@ -699,11 +725,12 @@ def create_many_related_manager(superclass, rel):
# Add the ones that aren't there already
self.through._default_manager.using(db).bulk_create([
self.through(**{
'%s_id' % source_field_name: self._pk_val,
'%s_id' % source_field_name: self._fk_val,
'%s_id' % target_field_name: obj_id,
})
for obj_id in new_ids
])
if self.reverse or source_field_name == self.source_field_name:
# Don't send the signal when we are inserting the
# duplicate data row for symmetrical reverse entries.
@@ -722,7 +749,7 @@ def create_many_related_manager(superclass, rel):
old_ids = set()
for obj in objs:
if isinstance(obj, self.model):
old_ids.add(obj.pk)
old_ids.add(self._get_fk_val(obj, target_field_name))
else:
old_ids.add(obj)
# Work out what DB we're operating on
@@ -736,7 +763,7 @@ def create_many_related_manager(superclass, rel):
model=self.model, pk_set=old_ids, using=db)
# Remove the specified objects from the join table
self.through._default_manager.using(db).filter(**{
source_field_name: self._pk_val,
source_field_name: self._fk_val,
'%s__in' % target_field_name: old_ids
}).delete()
if self.reverse or source_field_name == self.source_field_name:
@@ -756,7 +783,7 @@ def create_many_related_manager(superclass, rel):
instance=self.instance, reverse=self.reverse,
model=self.model, pk_set=None, using=db)
self.through._default_manager.using(db).filter(**{
source_field_name: self._pk_val
source_field_name: self._fk_val
}).delete()
if self.reverse or source_field_name == self.source_field_name:
# Don't send the signal when we are clearing the