Opened 2 years ago

Closed 6 months ago

#28767 closed Bug (fixed)

Incorrect value when annotating empty list as Value() on ArrayField.

Reported by: Matthew Schinckel Owned by:
Component: contrib.postgres Version: 2.2
Severity: Normal Keywords: annotate
Cc: Tomer Chachamu Triage Stage: Accepted
Has patch: no Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no


I have a nice simple minimal case that shows this.

You can try this on any model: auth.User was just convenient for example. You'll need at least one object in there to query.

from django.contrib.auth.models import User
from django.contrib.postgres.fields import ArrayField
from django.db.models.expressions import Value
from django.db.models import IntegerField

User.objects.annotate(foo=Value([1], output_field=ArrayField(IntegerField()))).first().foo
# Outputs [1], as expected

User.objects.annotate(foo=Value([], output_field=ArrayField(IntegerField()))).first().foo
# Outputs '{}', which is _not_ correct.

Change History (6)

comment:1 Changed 2 years ago by Matthew Schinckel

Still a problem in current development head.

Last edited 2 years ago by Matthew Schinckel (previous) (diff)

comment:2 Changed 2 years ago by Tim Graham

Triage Stage: UnreviewedAccepted

#28762 may be related if not a duplicate.

comment:3 Changed 2 years ago by Tomer Chachamu

I added an (expected failing) test in #28762 for this.

I think this ticket will be easier to fix after #28762 . The problem is that psycopg2 adapts the empty list to '{}'. We cannot simply send ARRAY[] because this causes ERROR: cannot determine type of empty array. However we can send '{}'::integer[].

ArrayField.db_type() is already implemented and returns 'integer[]' so we can pass that value to ArrayLiteral and always output it into the SQL.

This might break something else, we'll see.

Last edited 2 years ago by Tomer Chachamu (previous) (diff)

comment:4 Changed 23 months ago by Tomer Chachamu

Cc: Tomer Chachamu added

comment:5 Changed 6 months ago by GitHub <noreply@…>

In 654614b3:

Refs #28767 -- Added test for annotating Value() with empty list as an ArrayField.

Fixed in 3af695eda24b874486ee8be7e0d729761b3bdc71.

comment:6 Changed 6 months ago by felixxm

Resolution: fixed
Status: newclosed
Version: 1.112.2
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