Commit a4c20ae8 authored by Tim Graham's avatar Tim Graham
Browse files

Refs #24227 -- Fixed crash of ManyToManyField.value_from_object() on unsaved model instances. 

This behavior was removed in 67d98441
but is needed to prevent a crash in formtools.
parent 4f474607

django/db/models/fields/related.py

+2 −0
Original line number Diff line number Diff line
@@ -1565,6 +1565,8 @@ class ManyToManyField(RelatedField): 
        """

        Return the value of this field in the given model instance.

        """

        if obj.pk is None:

            return []

        qs = getattr(obj, self.attname).all()

        if qs._result_cache is not None:

            return [item.pk for item in qs]

tests/model_fields/test_manytomanyfield.py

+8 −0
Original line number Diff line number Diff line
@@ -6,6 +6,14 @@ from django.test.utils import isolate_apps 


class ManyToManyFieldTests(SimpleTestCase):



    @isolate_apps('model_fields')

    def test_value_from_object_instance_without_pk(self):

        class ManyToManyModel(models.Model):

            m2m = models.ManyToManyField('self', models.CASCADE)



        instance = ManyToManyModel()

        self.assertEqual(instance._meta.get_field('m2m').value_from_object(instance), [])



    def test_abstract_model_pending_operations(self):

        """

        Many-to-many fields declared on abstract models should not add lazy