#35275: Constraints validation fails on UniqueConstraint using OpClass -------------------------------------+------------------------------------- Reporter: Mathieu | Owner: nobody Kniewallner | Type: Bug | Status: new Component: Database | Version: dev layer (models, ORM) | Severity: Normal | Keywords: Triage Stage: | Has patch: 0 Unreviewed | Needs documentation: 0 | Needs tests: 0 Patch needs improvement: 0 | Easy pickings: 0 UI/UX: 0 | -------------------------------------+------------------------------------- Adding a `UniqueConstraint` using PostgreSQL-specific `OpClass` on a model breaks constraints validation performed when calling `validate_constraints` on a model when using PostgreSQL.
=== Minimal reproducer {{{#!python from django.contrib.postgres.indexes import OpClass from django.db import models from django.db.models.functions import Lower class Place(models.Model): name = models.CharField(max_length=255) class Meta: app_label = "opclass_issue" constraints = [ models.UniqueConstraint( OpClass(Lower("name"), name="text_pattern_ops"), name="lower_name_uniq", ) ] place = Place(name="Narnia") place.validate_constraints() }}} This leads to the following error: {{{ django.db.utils.ProgrammingError: syntax error at or near "text_pattern_ops" LINE 1: ...place" WHERE LOWER("opclass_issue_place"."name") text_patte... }}} Full SQL query that is generated: {{{#!sql SELECT 1 AS "a" FROM "opclass_issue_place" WHERE LOWER("opclass_issue_place"."name") text_pattern_ops = (LOWER('narnia') text_pattern_ops) LIMIT 1 }}} Just in case, this happens even though `django.contrib.postgres` is correctly installed in `INSTALLED_APPS`, so the issue is not related to that. I've also created a test and adapted the CI to run it in https://github.com/backmarket-oss/django/pull/2/files, which leads to https://github.com/backmarket- oss/django/actions/runs/8171237603/job/22339033423?pr=2 showing the failure. === Potential root cause `OpClass` wrapper should only make sense when creating the constraint, and should not be used when validating the constraint, as this leads to an invalid SQL query. Looking at the code for the PostgreSQL specific `ExclusionConstraint`, a similar conclusion was reached, and `OpClass` is explicitly removed in `validate` method: https://github.com/django/django/blob/4426b1a72dc289643e2ae8c190b8dc4b3a39daf7/django/contrib/postgres/constraints.py#L211-L216. === Potential fix Applying a similar fix as the one above in `UniqueConstraint`, showcased in https://github.com/backmarket-oss/django/pull/1/files applied on top of the other PR above, leads to https://github.com/backmarket- oss/django/actions/runs/8171242801/job/22339050847?pr=1 where the added test is now passing. If you think that this is the correct fix to apply, or have a lead for another fix, I'd be happy to make a proper pull request targeting Django repository. -- Ticket URL: <https://code.djangoproject.com/ticket/35275> Django <https://code.djangoproject.com/> The Web framework for perfectionists with deadlines. -- You received this message because you are subscribed to the Google Groups "Django updates" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-updates+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/django-updates/0107018e13ca0979-fa582a9e-c0cb-4892-9842-97c8207da856-000000%40eu-central-1.amazonses.com.