id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
28289	QuerySet.count() does not with work raw sql annotations on inherited model fields	Karolis Ryselis	Can Sarıgöl	"Consider these models


{{{
class BaseItem(models.Model):
    title = models.CharField(max_length=32)


class Item(BaseItem):
    pass
}}}

If I use a `RawSQL` annotation of `Item`'s queryset that includes one of the fields defined in `BaseItem` and call `.count()` on annotated queryset, it fails with the error:

`django.db.utils.OperationalError: (1054, ""Unknown column 'title' in 'field list'"")` (MySQL 5.7)

code to reproduce the bug with given models:
{{{
queryset = Item.objects.all()
queryset = queryset.annotate(title2=RawSQL(""title"", ()))
queryset.count() # crashes
}}}

I have tracked down what causes this bug. `Query.get_aggregation` method drops `INNER JOIN` required to select the `title` field. Specifically, this code drops it:
{{{
            if not inner_query.distinct:
                # If the inner query uses default select and it has some
                # aggregate annotations, then we must make sure the inner
                # query is grouped by the main model's primary key. However,
                # clearing the select clause can alter results if distinct is
                # used.
                if inner_query.default_cols and has_existing_annotations:
                    inner_query.group_by = [self.model._meta.pk.get_col(inner_query.get_initial_alias())]
                inner_query.default_cols = False
}}}
Code is taken from Django 1.8 but 1.11 looks the same.
`default_cols` is set to `False` and the `INNER JOIN` is dropped. Quick fix is to add a condition for setting `default_cols` to `False`:
{{{
            if not inner_query.distinct:
                # If the inner query uses default select and it has some
                # aggregate annotations, then we must make sure the inner
                # query is grouped by the main model's primary key. However,
                # clearing the select clause can alter results if distinct is
                # used.
                if inner_query.default_cols and has_existing_annotations:
                    inner_query.group_by = [self.model._meta.pk.get_col(inner_query.get_initial_alias())]
                if not has_existing_annotations:
                    inner_query.default_cols = False
}}}

I don't know if it could be done in a nicer way. I was able to reproduce this in 1.8.18 and 1.11.0"	Bug	closed	Database layer (models, ORM)	dev	Normal	fixed			Accepted	1	0	0	0	0	0