#16409: `defer()` and `only()` don't play nice with `annotate()`
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Reporter: mrmachine | Owner: nobody
Type: Bug | Status: new
Milestone: 1.4 | Component: Database layer
Version: SVN | (models, ORM)
Keywords: annotate defer only | Severity: Normal
count | Triage Stage: Unreviewed
Has patch: 0 | Easy pickings: 0
UI/UX: 0 |
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When adding `defer()` or `only()` to an existing query that used
`annotate()` to cut out some fields, I started getting IndexError
exceptions.
At first, I thought it was due to `aggregate_start` not being reduced by
the number of deferred fields in `QuerySet.iterator()`, but when I looked
at the SQL being generated I saw that ALL fields were being dropped from
the query, except for the annotation. I suspect that even if this is
fixed, `aggregate_start` will also need to be reduced by the number of
deferred fields.
Here's the traceback:
{{{
>>> from django.db.models import Count
>>> from django.contrib.auth.models import *
>>> from django.contrib.admin.models import *
>>> User.objects.annotate(Count('logentry'))
[<User: manager>, <User: trak:1:10>, <User: admin>, <User: trak:3:5>,
<User: trak:1:24>, <User: trak:3:9>, <User: trak:1:3>, <User: trak:4:11>,
<User: trak:5:21>, <User: trak:1:14>, <User: trak:1:15>, <User: trak:1:2>,
<User: trak:4:18>, <User: trak:4:19>, <User: trak:5:17>, <User: trak:3:6>,
<User: trak:1:23>, <User: trak:3:16>, <User: trak:5:22>, <User:
trak:4:12>, '...(remaining elements truncated)...']
>>> User.objects.annotate(Count('logentry')).defer('first_name')
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/Users/mrmachine/myproject/django/db/models/query.py", line 69, in
__repr__
data = list(self[:REPR_OUTPUT_SIZE + 1])
File "/Users/mrmachine/myproject/django/db/models/query.py", line 84, in
__len__
self._result_cache.extend(self._iter)
File "/Users/mrmachine/myproject/django/db/models/query.py", line 300,
in iterator
setattr(obj, aggregate, row[i+aggregate_start])
IndexError: tuple index out of range
}}}
Here's the generated SQL:
{{{
>>> str(User.objects.annotate(Count('logentry')).query)
'SELECT "auth_user"."id", "auth_user"."username",
"auth_user"."first_name", "auth_user"."last_name", "auth_user"."email",
"auth_user"."password", "auth_user"."is_staff", "auth_user"."is_active",
"auth_user"."is_superuser", "auth_user"."last_login",
"auth_user"."date_joined", COUNT("django_admin_log"."id") AS
"logentry__count" FROM "auth_user" LEFT OUTER JOIN "django_admin_log" ON
("auth_user"."id" = "django_admin_log"."user_id") GROUP BY
"auth_user"."id", "auth_user"."username", "auth_user"."first_name",
"auth_user"."last_name", "auth_user"."email", "auth_user"."password",
"auth_user"."is_staff", "auth_user"."is_active",
"auth_user"."is_superuser", "auth_user"."last_login",
"auth_user"."date_joined"'
>>>
str(User.objects.annotate(Count('logentry')).defer('first_name').query)
'SELECT COUNT("django_admin_log"."id") AS "logentry__count" FROM
"auth_user" LEFT OUTER JOIN "django_admin_log" ON ("auth_user"."id" =
"django_admin_log"."user_id") GROUP BY "auth_user"."id",
"auth_user"."username", "auth_user"."first_name", "auth_user"."last_name",
"auth_user"."email", "auth_user"."password", "auth_user"."is_staff",
"auth_user"."is_active", "auth_user"."is_superuser",
"auth_user"."last_login", "auth_user"."date_joined"'
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/16409>
Django <https://code.djangoproject.com/>
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