Django falsely claims "There is no unique constraint matching given keys for referenced table"

Question

If I add the following class to my model, all works fine on migration.

class BeursCheck(models.Model):
    order = models.IntegerField(default=None)
    painting = models.ForeignKey(Painting, related_name='beursCheck',primary_key=True)

However, if I add this field..

mturk_assignment = models.ForeignKey(
    'mturk.MtAssignment', null=True, blank=True,
    related_name='+', on_delete=models.SET_NULL, unique=True
)

It fails with error

django.db.utils.ProgrammingError: there is no unique constraint matching given keys for referenced table "mturk_mtassignment"

This field relates to MtAssignemnt, which has a unique key. This related answered even says so.

class MtAssignment(MtModelBase):
     id = models.CharField(max_length=128, primary_key=True)

Ernst · Answer 1 · 2018-02-09T16:12:44.877

0

try change to:

from mturk.models import MtAssigmnet

    mturk_assignment = models.ForeignKey(
        MtAssignment, null=True, blank=True,
        related_name='+', on_delete=models.SET_NULL
    )

edited Feb 09 '18 at 16:12

answered Feb 09 '18 at 16:02

Ernst

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the 'mturk.' refers to another app, where the MtAssignment is located. – Mitchell van Zuylen Feb 09 '18 at 16:09
@MitchellvanZuylen check сhanges in my answer – Ernst Feb 09 '18 at 16:11
Regretfully, no changes. – Mitchell van Zuylen Feb 12 '18 at 15:02
@MitchellvanZuylen try to change related_name to 'mturk_assignments' – Ernst Feb 12 '18 at 15:45
Did that to no avail – Mitchell van Zuylen Feb 12 '18 at 17:24

Django falsely claims "There is no unique constraint matching given keys for referenced table"

1 Answers1