Fixed #22217 - ManyToManyField.through_fields fixes.
- Docs description of arguments mix up. - Keep it from erroneously masking E332 check. - Add checks E338 and E339, tweak message of E337.
This commit is contained in:
Akis Kesoglou
Ramiro Morales
parent
f4d91638fc
commit
aaad3e27ac
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@ -1904,21 +1904,7 @@ class ManyToManyField(RelatedField):
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)
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)
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elif self.rel.through_fields is not None:
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if not len(self.rel.through_fields) >= 2 or not (self.rel.through_fields[0] and self.rel.through_fields[1]):
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errors.append(
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checks.Error(
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("The field is given an iterable for through_fields, "
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"which does not provide the names for both link fields "
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"that Django should use for the relation through model "
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"'%s'.") % qualified_model_name,
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hint=None,
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obj=self,
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id='fields.E337',
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)
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)
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elif not isinstance(self.rel.through, six.string_types):
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else:
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assert from_model is not None, \
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"ManyToManyField with intermediate " \
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@ -2018,6 +2004,78 @@ class ManyToManyField(RelatedField):
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id='fields.E336',
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)
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)
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# Validate `through_fields`
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if self.rel.through_fields is not None:
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# Validate that we're given an iterable of at least two items
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# and that none of them is "falsy"
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if not (len(self.rel.through_fields) >= 2 and
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self.rel.through_fields[0] and self.rel.through_fields[1]):
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errors.append(
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checks.Error(
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("Field specifies 'through_fields' but does not "
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"provide the names of the two link fields that should be "
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"used for the relation through model "
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"'%s'.") % qualified_model_name,
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hint=("Make sure you specify 'through_fields' as "
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"through_fields=('field1', 'field2')"),
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obj=self,
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id='fields.E337',
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)
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)
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# Validate the given through fields -- they should be actual
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# fields on the through model, and also be foreign keys to the
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# expected models
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else:
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assert from_model is not None, \
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"ManyToManyField with intermediate " \
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"tables cannot be checked if you don't pass the model " \
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"where the field is attached to."
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source, through, target = from_model, self.rel.through, self.rel.to
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source_field_name, target_field_name = self.rel.through_fields[:2]
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for field_name, related_model in ((source_field_name, source),
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(target_field_name, target)):
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possible_field_names = []
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for f in through._meta.fields:
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if hasattr(f, 'rel') and getattr(f.rel, 'to', None) == related_model:
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possible_field_names.append(f.name)
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if possible_field_names:
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hint = ("Did you mean one of the following foreign "
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"keys to '%s': %s?") % (related_model._meta.object_name,
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', '.join(possible_field_names))
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else:
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hint = None
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try:
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field = through._meta.get_field(field_name)
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except FieldDoesNotExist:
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errors.append(
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checks.Error(
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("The intermediary model '%s' has no field '%s'.") % (
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qualified_model_name, field_name),
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hint=hint,
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obj=self,
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id='fields.E338',
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)
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)
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else:
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if not (hasattr(field, 'rel') and
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getattr(field.rel, 'to', None) == related_model):
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errors.append(
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checks.Error(
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"'%s.%s' is not a foreign key to '%s'." % (
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through._meta.object_name, field_name,
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related_model._meta.object_name),
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hint=hint,
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obj=self,
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id='fields.E339',
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)
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)
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return errors
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def deconstruct(self):
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@ -2104,9 +2162,6 @@ class ManyToManyField(RelatedField):
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(link_field_name is None or link_field_name == f.name):
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setattr(self, cache_attr, getattr(f, attr))
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return getattr(self, cache_attr)
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# We only reach here if we're given an invalid field name via the
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# `through_fields` argument
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raise FieldDoesNotExist(link_field_name)
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def _get_m2m_reverse_attr(self, related, attr):
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"Function that can be curried to provide the related accessor or DB column name for the m2m table"
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@ -2133,12 +2188,7 @@ class ManyToManyField(RelatedField):
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elif link_field_name is None or link_field_name == f.name:
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setattr(self, cache_attr, getattr(f, attr))
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break
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try:
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return getattr(self, cache_attr)
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except AttributeError:
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# We only reach here if we're given an invalid reverse field
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# name via the `through_fields` argument
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raise FieldDoesNotExist(link_field_name)
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def value_to_string(self, obj):
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data = ''
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@ -94,7 +94,9 @@ Related Fields
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* **fields.E334**: The model is used as an intermediate model by ``<model>``, but it has more than one foreign key from ``<model>``, which is ambiguous. You must specify which foreign key Django should use via the through_fields keyword argument.
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* **fields.E335**: The model is used as an intermediate model by ``<model>``, but it has more than one foreign key to ``<model>``, which is ambiguous. You must specify which foreign key Django should use via the through_fields keyword argument.
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* **fields.E336**: The model is used as an intermediary model by ``<model>``, but it does not have foreign key to ``<model>`` or ``<model>``.
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* **fields.E337**: The field is given an iterable for through_fields, which does not provide the names for both link fields that Django should use for the relation through <model>.
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* **fields.E337**: Field specifies ``through_fields`` but does not provide the names of the two link fields that should be used for the relation through ``<model>``.
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* **fields.E338**: The intermediary model ``<through model>`` has no field ``<field name>``.
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* **fields.E339**: ``<model>.<field name>`` is not a foreign key to ``<model>``.
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Signals
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~~~~~~~
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@ -1353,11 +1353,11 @@ that control how the relationship functions.
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class Group(models.Model):
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name = models.CharField(max_length=128)
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members = models.ManyToManyField(Person, through='Membership', through_fields=('person', 'group'))
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members = models.ManyToManyField(Person, through='Membership', through_fields=('group', 'person'))
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class Membership(models.Model):
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person = models.ForeignKey(Person)
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group = models.ForeignKey(Group)
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person = models.ForeignKey(Person)
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inviter = models.ForeignKey(Person, related_name="membership_invites")
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invite_reason = models.CharField(max_length=64)
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@ -1368,9 +1368,10 @@ that control how the relationship functions.
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above.
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``through_fields`` accepts a 2-tuple ``('field1', 'field2')``, where
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``field1`` is the name of the foreign key to the target model (``person``
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in this case), and ``field2`` the name of the foreign key to the model the
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:class:`ManyToManyField` is defined on (``group`` in this case).
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``field1`` is the name of the foreign key to the model the
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:class:`ManyToManyField` is defined on (``group`` in this case), and
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``field2`` the name of the foreign key to the target model (``person``
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in this case).
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When you have more than one foreign key on an intermediary model to any
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(or even both) of the models participating in a many-to-many relationship,
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@ -440,12 +440,12 @@ explicit declaration defines how the two models are related.
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There are a few restrictions on the intermediate model:
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* Your intermediate model must contain one - and *only* one - foreign key
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to the target model (this would be ``Person`` in our example), or you must
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to the source model (this would be ``Group`` in our example), or you must
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explicitly specify the foreign keys Django should use for the relationship
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using :attr:`ManyToManyField.through_fields <ManyToManyField.through_fields>`.
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If you have more than one foreign key and ``through_fields`` is not
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specified, a validation error will be raised. A similar restriction applies
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to the foreign key to the source model (this would be ``Group`` in our
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to the foreign key to the target model (this would be ``Person`` in our
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example).
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* For a model which has a many-to-many relationship to itself through an
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@ -240,6 +240,32 @@ class RelativeFieldTests(IsolatedModelsTestCase):
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]
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self.assertEqual(errors, expected)
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def test_symmetric_self_reference_with_intermediate_table_and_through_fields(self):
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"""Using through_fields in a m2m with an intermediate model shouldn't mask its incompatibility with symmetry."""
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class Person(models.Model):
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# Explicit symmetrical=True.
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friends = models.ManyToManyField('self',
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symmetrical=True,
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through="Relationship",
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through_fields=('first', 'second'))
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class Relationship(models.Model):
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first = models.ForeignKey(Person, related_name="rel_from_set")
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second = models.ForeignKey(Person, related_name="rel_to_set")
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referee = models.ForeignKey(Person, related_name="referred")
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field = Person._meta.get_field('friends')
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errors = field.check(from_model=Person)
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expected = [
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Error(
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'Many-to-many fields with intermediate tables must not be symmetrical.',
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hint=None,
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obj=field,
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id='fields.E332',
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),
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]
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self.assertEqual(errors, expected)
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def test_foreign_key_to_abstract_model(self):
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class Model(models.Model):
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foreign_key = models.ForeignKey('AbstractModel')
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@ -1071,43 +1097,69 @@ class M2mThroughFieldsTests(IsolatedModelsTestCase):
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ValueError, 'Cannot specify through_fields without a through model',
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models.ManyToManyField, Fan, through_fields=('f1', 'f2'))
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def test_invalid_m2m_field(self):
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def test_invalid_order(self):
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"""
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Tests that providing invalid source field name to ManyToManyField.through_fields
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raises FieldDoesNotExist.
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Tests that mixing up the order of link fields to ManyToManyField.through_fields
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triggers validation errors.
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"""
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class Fan(models.Model):
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pass
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class Event(models.Model):
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invitees = models.ManyToManyField(Fan, through='Invitation', through_fields=('invalid_field', 'invitee'))
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invitees = models.ManyToManyField(Fan, through='Invitation', through_fields=('invitee', 'event'))
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class Invitation(models.Model):
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event = models.ForeignKey(Event)
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invitee = models.ForeignKey(Fan)
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inviter = models.ForeignKey(Fan, related_name='+')
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with self.assertRaisesMessage(FieldDoesNotExist, 'invalid_field'):
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Event().invitees.all()
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field = Event._meta.get_field('invitees')
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errors = field.check(from_model=Event)
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expected = [
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Error(
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("'Invitation.invitee' is not a foreign key to 'Event'."),
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hint="Did you mean one of the following foreign keys to 'Event': event?",
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obj=field,
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id='fields.E339'),
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Error(
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("'Invitation.event' is not a foreign key to 'Fan'."),
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hint="Did you mean one of the following foreign keys to 'Fan': invitee, inviter?",
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obj=field,
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id='fields.E339'),
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]
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self.assertEqual(expected, errors)
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def test_invalid_m2m_reverse_field(self):
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def test_invalid_field(self):
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"""
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Tests that providing invalid reverse field name to ManyToManyField.through_fields
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raises FieldDoesNotExist.
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Tests that providing invalid field names to ManyToManyField.through_fields
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triggers validation errors.
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"""
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class Fan(models.Model):
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pass
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class Event(models.Model):
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invitees = models.ManyToManyField(Fan, through='Invitation', through_fields=('event', 'invalid_field'))
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invitees = models.ManyToManyField(Fan, through='Invitation', through_fields=('invalid_field_1', 'invalid_field_2'))
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class Invitation(models.Model):
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event = models.ForeignKey(Event)
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invitee = models.ForeignKey(Fan)
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inviter = models.ForeignKey(Fan, related_name='+')
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with self.assertRaisesMessage(FieldDoesNotExist, 'invalid_field'):
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Event().invitees.all()
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field = Event._meta.get_field('invitees')
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errors = field.check(from_model=Event)
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expected = [
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Error(
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("The intermediary model 'invalid_models_tests.Invitation' has no field 'invalid_field_1'."),
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hint="Did you mean one of the following foreign keys to 'Event': event?",
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obj=field,
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id='fields.E338'),
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Error(
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("The intermediary model 'invalid_models_tests.Invitation' has no field 'invalid_field_2'."),
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hint="Did you mean one of the following foreign keys to 'Fan': invitee, inviter?",
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obj=field,
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id='fields.E338'),
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]
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self.assertEqual(expected, errors)
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def test_explicit_field_names(self):
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"""
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@ -1129,11 +1181,11 @@ class M2mThroughFieldsTests(IsolatedModelsTestCase):
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errors = field.check(from_model=Event)
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expected = [
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Error(
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("The field is given an iterable for through_fields, "
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"which does not provide the names for both link fields "
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"that Django should use for the relation through model "
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"'invalid_models_tests.Invitation'."),
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hint=None,
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("Field specifies 'through_fields' but does not provide the names "
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"of the two link fields that should be used for the relation "
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"through model 'invalid_models_tests.Invitation'."),
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hint=("Make sure you specify 'through_fields' as "
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"through_fields=('field1', 'field2')"),
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obj=field,
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id='fields.E337')]
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self.assertEqual(expected, errors)
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