#31198: CheckConstraints with F objects don't apply on SQLite
-------------------------------------+-------------------------------------
Reporter: Adam | Owner: nobody
(Chainz) Johnson |
Type: Bug | Status: new
Component: Database | Version: master
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 |
-------------------------------------+-------------------------------------
Take this model with CheckConstraint:
{{{
class Book(models.Model):
percent_read = models.PositiveIntegerField()
percent_unread = models.PositiveIntegerField()
percent_ignored = models.PositiveIntegerField()
def __str__(self):
return f"{self.id} - {self.percent_read}% read"
class Meta:
constraints = [
models.CheckConstraint(
check=models.Q(
percent_read=(
100
- models.F("percent_unread")
- models.F("percent_ignored")
)
),
name="percentages_sum_100",
)
]
}}}
Applying the migration to create the constraint works on MariaDB but fails
on SQLite.
The `sqlmigrate` output on SQLite shows the F objects get resolved to the
full table name, which is what breaks during renaming phase in the
migration:
{{{
$ python manage.py sqlmigrate core 0002
BEGIN;
--
-- Create constraint percentages_sum_100 on model book
--
CREATE TABLE "new__core_book" ("id" integer NOT NULL PRIMARY KEY
AUTOINCREMENT, "percent_read" integer unsigned NOT NULL CHECK
("percent_read" >= 0), "percent_unread" integer unsigned NOT NULL CHECK
("percent_unread" >= 0), "percent_ignored" integer unsigned NOT NULL CHECK
("percent_ignored" >= 0), CONSTRAINT "percentages_sum_100" CHECK
("percent_read" = ((100 - "new__core_book"."percent_unread") -
"new__core_book"."percent_ignored")));
INSERT INTO "new__core_book" ("id", "percent_read", "percent_unread",
"percent_ignored") SELECT "id", "percent_read", "percent_unread",
"percent_ignored" FROM "core_book";
DROP TABLE "core_book";
ALTER TABLE "new__core_book" RENAME TO "core_book";
COMMIT;
$ python manage.py migrate
...
django.db.utils.DatabaseError: malformed database schema (core_book) - no
such column: new__core_book.percent_unread
}}}
Full repo for reproduction: https://github.com/adamchainz/django-issue-
check-constraint-reference
--
Ticket URL: <https://code.djangoproject.com/ticket/31198>
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