#24986: Selecting distinct on lower() function throws AttributeError("'Func'
object
has no attribute 'column'")
-------------------------------------+-------------------------------------
Reporter: wbar | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.8
(models, ORM) |
Severity: Release blocker | Resolution:
Keywords: F(), ORM, distinct | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by wbar:
Old description:
> I have simple table:
>
> {{{
> class Author(models.Model):
> name = models.CharField(max_length=40)
> }}}
>
> I want to write Query using Django ORM to be similar to:
>
> {{{
> SELECT DISTINCT LOWER(name) from my_app_author;
> }}}
>
> I finally ended with:
>
> {{{
> Author.objects.annotate(
> name_lower=Func(F('name'), function='lower')
> ).distinct('name_lower')
> }}}
>
> But I'm receiving error:
>
> {{{
> Traceback (most recent call last):
> File "/opt/venv/lib/python3.4/site-packages/django/db/models/query.py",
> line 138, in __repr__
> data = list(self[:REPR_OUTPUT_SIZE + 1])
> File "/opt/venv/lib/python3.4/site-packages/django/db/models/query.py",
> line 162, in __iter__
> self._fetch_all()
> File "/opt/venv/lib/python3.4/site-packages/django/db/models/query.py",
> line 965, in _fetch_all
> self._result_cache = list(self.iterator())
> File "/opt/venv/lib/python3.4/site-packages/django/db/models/query.py",
> line 238, in iterator
> results = compiler.execute_sql()
> File "/opt/venv/lib/python3.4/site-
> packages/django/db/models/sql/compiler.py", line 829, in execute_sql
> sql, params = self.as_sql()
> File "/opt/venv/lib/python3.4/site-
> packages/django/db/models/sql/compiler.py", line 381, in as_sql
> distinct_fields = self.get_distinct()
> File "/opt/venv/lib/python3.4/site-
> packages/django/db/models/sql/compiler.py", line 545, in get_distinct
> result.append("%s.%s" % (qn(alias), qn2(target.column)))
> AttributeError: 'Func' object has no attribute 'column'
> }}}
>
> but when i write:
>
> {{{
> Author.objects.annotate(
> name_lower=Func(F('name'), function='lower')
> ).distinct('something')
> }}}
>
> I'm receiving an error:
>
> {{{
> django.core.exceptions.FieldError:
> Cannot resolve keyword 'something' into field.
> Choices are: id, name, name_lower, src_id
> }}}
New description:
I have simple table:
{{{
class Author(models.Model):
name = models.CharField(max_length=40)
}}}
I want to write Query using Django ORM to be similar to:
{{{
SELECT DISTINCT LOWER(name) from my_app_author;
}}}
I finally ended with:
{{{
Author.objects.annotate(
name_lower=Func(F('name'), function='lower')
).distinct('name_lower')
}}}
But I'm receiving error:
{{{
Traceback (most recent call last):
File "/opt/venv/lib/python3.4/site-packages/django/db/models/query.py",
line 138, in __repr__
data = list(self[:REPR_OUTPUT_SIZE + 1])
File "/opt/venv/lib/python3.4/site-packages/django/db/models/query.py",
line 162, in __iter__
self._fetch_all()
File "/opt/venv/lib/python3.4/site-packages/django/db/models/query.py",
line 965, in _fetch_all
self._result_cache = list(self.iterator())
File "/opt/venv/lib/python3.4/site-packages/django/db/models/query.py",
line 238, in iterator
results = compiler.execute_sql()
File "/opt/venv/lib/python3.4/site-
packages/django/db/models/sql/compiler.py", line 829, in execute_sql
sql, params = self.as_sql()
File "/opt/venv/lib/python3.4/site-
packages/django/db/models/sql/compiler.py", line 381, in as_sql
distinct_fields = self.get_distinct()
File "/opt/venv/lib/python3.4/site-
packages/django/db/models/sql/compiler.py", line 545, in get_distinct
result.append("%s.%s" % (qn(alias), qn2(target.column)))
AttributeError: 'Func' object has no attribute 'column'
}}}
but when i write:
{{{
Author.objects.annotate(
name_lower=Func(F('name'), function='lower')
).distinct('something')
}}}
I'm receiving an error:
{{{
django.core.exceptions.FieldError:
Cannot resolve keyword 'something' into field.
Choices are: id, name, name_lower, src_id
}}}
As database driver I'm using `'ENGINE':
'django.contrib.gis.db.backends.postgis'`
--
--
Ticket URL: <https://code.djangoproject.com/ticket/24986#comment:2>
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