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Fixed #30 -- Simplified PolymorphicTypeField by using a callable limit_choices_to. #31

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Merged
charettes merged 1 commit into from
Jun 1, 2016
Merged

Fixed #30 -- Simplified PolymorphicTypeField by using a callable limit_choices_to. #31

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47 changes: 21 additions & 26 deletions polymodels/fields.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@
from django.contrib.contenttypes.models import ContentType
from django.db.models import ForeignKey, Q
from django.db.models.fields import NOT_PROVIDED
from django.db.models.fields.related import ManyToOneRel, RelatedField
from django.db.models.fields.related import RelatedField
from django.utils.deconstruct import deconstructible
from django.utils.functional import LazyObject
from django.utils.six import string_types
Expand All @@ -18,28 +18,26 @@
from .utils import get_content_type


class PolymorphicManyToOneRel(ManyToOneRel):
"""
Relationship that generates a `limit_choices_to` based on it's polymorphic type subclasses.
"""
class LimitChoicesToSubclasses(object):
def __init__(self, field, limit_choices_to):
self.field = field
self.limit_choices_to = limit_choices_to

@property
def limit_choices_to(self):
subclasses_lookup = self.polymorphic_type.subclasses_lookup('pk')
limit_choices_to = self._limit_choices_to
def value(self):
subclasses_lookup = self.field.polymorphic_type.subclasses_lookup('pk')
limit_choices_to = self.limit_choices_to
if limit_choices_to is None:
limit_choices_to = subclasses_lookup
limit_choices_to = subclasses_lookup.copy()
elif isinstance(limit_choices_to, dict):
limit_choices_to = dict(limit_choices_to, **subclasses_lookup)
elif isinstance(limit_choices_to, Q):
limit_choices_to = limit_choices_to & Q(**subclasses_lookup)
self.__dict__['limit_choices_to'] = limit_choices_to
self.__dict__['value'] = limit_choices_to
return limit_choices_to

@limit_choices_to.setter
def limit_choices_to(self, value):
self._limit_choices_to = value
self.__dict__.pop('limit_choices_to', None)
def __call__(self):
return self.value


class LazyPolymorphicTypeQueryset(LazyObject):
Expand All @@ -51,7 +49,7 @@ def _setup(self):
remote_field = self.__dict__.get('remote_field')
db = self.__dict__.get('db')
self._wrapped = get_remote_model(remote_field)._default_manager.using(db).complex_filter(
remote_field.limit_choices_to
remote_field.limit_choices_to()
)


Expand Down Expand Up @@ -81,21 +79,19 @@ class PolymorphicTypeField(ForeignKey):
description = _(
'Content type of a subclass of %(type)s'
)
rel_class = PolymorphicManyToOneRel

def __init__(self, polymorphic_type, *args, **kwargs):
if not isinstance(polymorphic_type, string_types):
self.validate_polymorphic_type(polymorphic_type)
self.polymorphic_type = polymorphic_type
limit_choices_to = LimitChoicesToSubclasses(self, kwargs.pop('limit_choices_to', None))
defaults = {
'to': ContentType,
'related_name': '+',
'limit_choices_to': limit_choices_to,
}
# TODO: Remove when support for Django 1.8 is dropped.
if not hasattr(ForeignKey, 'rel_class'):
defaults['rel_class'] = PolymorphicManyToOneRel
defaults.update(kwargs)
defaults.update(**kwargs)
super(PolymorphicTypeField, self).__init__(*args, **defaults)
get_remote_field(self).polymorphic_type = polymorphic_type

def validate_polymorphic_type(self, model):
if not isclass(model) or not issubclass(model, BasePolymorphicModel):
Expand All @@ -106,12 +102,11 @@ def validate_polymorphic_type(self, model):

def contribute_to_class(self, cls, name):
super(PolymorphicTypeField, self).contribute_to_class(cls, name)
polymorphic_type = get_remote_field(self).polymorphic_type
polymorphic_type = self.polymorphic_type
if (isinstance(polymorphic_type, string_types) or
polymorphic_type._meta.pk is None):
def resolve_polymorphic_type(model, related_model, field):
field.validate_polymorphic_type(related_model)
get_remote_field(field).polymorphic_type = related_model
field.do_polymorphic_type(related_model)
lazy_related_operation(resolve_polymorphic_type, cls, polymorphic_type, field=self)
else:
Expand All @@ -121,18 +116,18 @@ def do_polymorphic_type(self, polymorphic_type):
if self.default is NOT_PROVIDED and not self.null:
opts = polymorphic_type._meta
self.default = ContentTypeReference(opts.app_label, opts.model_name)
self.polymorphic_type = polymorphic_type
self.type = polymorphic_type.__name__
self.error_messages['invalid'] = (
'Specified content type is not of a subclass of %s.' % polymorphic_type._meta.object_name
)

def formfield(self, **kwargs):
db = kwargs.pop('using', None)
remote_model = get_remote_model(get_remote_field(self))
if isinstance(remote_model, string_types):
if isinstance(self.polymorphic_type, string_types):
raise ValueError(
"Cannot create form field for %r yet, because its related model %r has not been loaded yet" % (
self.name, remote_model
self.name, self.polymorphic_type
)
)
defaults = {
Expand Down
43 changes: 13 additions & 30 deletions tests/test_fields.py
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Original file line number Diff line number Diff line change
Expand Up @@ -43,41 +43,24 @@ def test_limit_choices_to(self):
"""
Make sure existing `limit_choices_to` are taken into consideration
"""
type_field = Trait._meta.get_field('trait_type')
remote_field = get_remote_field(type_field)

# Make sure it's cached
limit_choices_to = remote_field.limit_choices_to
self.assertIn('limit_choices_to', remote_field.__dict__)

extra_limit_choices_to = {'app_label': 'polymodels'}

# Make sure it works with existing dict `limit_choices_to`
remote_field.limit_choices_to = extra_limit_choices_to
# Cache should be cleared
self.assertNotIn('limit_choices_to', remote_field.__dict__)
field = PolymorphicTypeField(Trait, on_delete=models.CASCADE)
remote_field = get_remote_field(field)
subclasses_lookup = Trait.subclasses_lookup('pk')
self.assertEqual(remote_field.limit_choices_to(), subclasses_lookup)
# Test dict() limit_choices_to.
limit_choices_to = {'app_label': 'polymodels'}
field = PolymorphicTypeField(Trait, on_delete=models.CASCADE, limit_choices_to=limit_choices_to)
remote_field = get_remote_field(field)
self.assertEqual(
remote_field.limit_choices_to,
dict(extra_limit_choices_to, **limit_choices_to)
remote_field.limit_choices_to(), dict(subclasses_lookup, **limit_choices_to)
)

# Make sure it works with existing Q `limit_choices_to`
remote_field.limit_choices_to = Q(**extra_limit_choices_to)
# Cache should be cleared
self.assertNotIn('limit_choices_to', remote_field.__dict__)
remote_field_limit_choices_to = remote_field.limit_choices_to
self.assertEqual(remote_field_limit_choices_to.connector, Q.AND)
self.assertFalse(remote_field_limit_choices_to.negated)
# Test Q() limit_choices_to.
field = PolymorphicTypeField(Trait, on_delete=models.CASCADE, limit_choices_to=Q(**limit_choices_to))
remote_field = get_remote_field(field)
self.assertEqual(
remote_field_limit_choices_to.children,
list(extra_limit_choices_to.items()) + list(limit_choices_to.items())
str(remote_field.limit_choices_to()), str(Q(**limit_choices_to) & Q(**subclasses_lookup))
)

# Re-assign the original value
remote_field.limit_choices_to = None
# Cache should be cleared
self.assertNotIn('limit_choices_to', remote_field.__dict__)

def test_invalid_type(self):
trait = Trait.objects.create()
snake_type = get_content_type(Snake)
Expand Down