#24233: group-by column construction is broken
----------------------------------------------+-----------------------
     Reporter:  megatrump                     |      Owner:  nobody
         Type:  Bug                           |     Status:  new
    Component:  Database layer (models, ORM)  |    Version:  1.8alpha1
     Severity:  Normal                        |   Keywords:
 Triage Stage:  Unreviewed                    |  Has patch:  0
Easy pickings:  0                             |      UI/UX:  0
----------------------------------------------+-----------------------
 I recently moved to 1.8alpha version from an older version django-e9d1f11
 and I started seeing this error. Looks like the way group by is
 constructed has changed. I am using postgres database.

 I could reproduce the behavior with a simple model.
 Here is the model that I have.

 {{{
 class everydaycost(models.Model):
     cost = models.DecimalField(max_digits=20, decimal_places=2)
     rev = models.DecimalField(max_digits=20, decimal_places=2)
     ts = models.DateField(db_index=True)
 }}}

 I am trying to get roi (rev/cost) for each day of week.

 {{{
 $ python manage.py shell
 Python 2.7.5 (default, Mar  9 2014, 22:15:05)
 [GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.0.68)] on darwin
 Type "help", "copyright", "credits" or "license" for more information.
 (InteractiveConsole)
 >>>
 >>> from testgroupby.models import *
 >>> from django.db.models import Q, Count, Min, Sum, Func, FloatField
 >>> qs = everydaycost.objects.all()
 >>> qs = qs.extra(select={'dow': "TO_CHAR(ts, 'D')"})
 >>> qs = qs.values('dow')
 >>> qs = qs.annotate(sum_cost=Sum('cost'))
 >>> qs = qs.annotate(sum_rev=Sum('rev'))
 >>> qs = qs.annotate(roi=Func(A='CAST(Sum("rev") as numeric)',
 B='CAST(Sum("cost") as numeric)',
 ...                 template='ROUND(COALESCE(%(A)s / NULLIF(%(B)s,0), 0),
 2)', output_field=FloatField()))
 >>> print qs
 DEBUG    (0.002) SELECT (TO_CHAR(ts, 'D')) AS "dow",
 SUM("testgroupby_everydaycost"."cost") AS "sum_cost",
 SUM("testgroupby_everydaycost"."rev") AS "sum_rev",
 ROUND(COALESCE(CAST(Sum("rev") as numeric) / NULLIF(CAST(Sum("cost") as
 numeric),0), 0), 2) AS "roi" FROM "testgroupby_everydaycost" GROUP BY
 (TO_CHAR(ts, 'D')), ROUND(COALESCE(CAST(Sum("rev") as numeric) /
 NULLIF(CAST(Sum("cost") as numeric),0), 0), 2) LIMIT 21; args=()
 Traceback (most recent call last):
   File "<console>", line 1, in <module>
   File "/Downloads/Django-1.8a1/django/db/models/query.py", line 139, in
 __repr__
     data = list(self[:REPR_OUTPUT_SIZE + 1])
   File "/Downloads/Django-1.8a1/django/db/models/query.py", line 163, in
 __iter__
     self._fetch_all()
   File "/Downloads/Django-1.8a1/django/db/models/query.py", line 955, in
 _fetch_all
     self._result_cache = list(self.iterator())
   File "/Downloads/Django-1.8a1/django/db/models/query.py", line 1075, in
 iterator
     for row in self.query.get_compiler(self.db).results_iter():
   File "/Downloads/Django-1.8a1/django/db/models/sql/compiler.py", line
 780, in results_iter
     results = self.execute_sql(MULTI)
   File "/Downloads/Django-1.8a1/django/db/models/sql/compiler.py", line
 826, in execute_sql
     cursor.execute(sql, params)
   File "/Downloads/Django-1.8a1/django/db/backends/utils.py", line 80, in
 execute
     return super(CursorDebugWrapper, self).execute(sql, params)
   File "/Downloads/Django-1.8a1/django/db/backends/utils.py", line 65, in
 execute
     return self.cursor.execute(sql, params)
   File "/Downloads/Django-1.8a1/django/db/utils.py", line 95, in __exit__
     six.reraise(dj_exc_type, dj_exc_value, traceback)
   File "/Downloads/Django-1.8a1/django/db/backends/utils.py", line 65, in
 execute
     return self.cursor.execute(sql, params)
 ProgrammingError: aggregate functions are not allowed in GROUP BY
 LINE 1: ... GROUP BY (TO_CHAR(ts, 'D')), ROUND(COALESCE(CAST(Sum("rev")...
                                                              ^

 >>> print qs.query
 SELECT (TO_CHAR(ts, 'D')) AS "dow", SUM("testgroupby_everydaycost"."cost")
 AS "sum_cost", SUM("testgroupby_everydaycost"."rev") AS "sum_rev",
 ROUND(COALESCE(CAST(Sum("rev") as numeric) / NULLIF(CAST(Sum("cost") as
 numeric),0), 0), 2) AS "roi" FROM "testgroupby_everydaycost" GROUP BY
 (TO_CHAR(ts, 'D')), ROUND(COALESCE(CAST(Sum("rev") as numeric) /
 NULLIF(CAST(Sum("cost") as numeric),0), 0), 2)
 >>>
 }}}

 With earlier version, this worked fine for me.

 {{{
 $ python manage.py shell
 Python 2.7.5 (default, Mar  9 2014, 22:15:05)
 [GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.0.68)] on darwin
 Type "help", "copyright", "credits" or "license" for more information.
 (InteractiveConsole)
 >>>
 >>> from testgroupby.models import *
 >>> from django.db.models import Q, Count, Min, Sum, Func, FloatField
 >>> qs = everydaycost.objects.all()
 >>> qs = qs.extra(select={'dow': "TO_CHAR(ts, 'D')"})
 >>> qs = qs.values('dow')
 >>> qs = qs.annotate(sum_cost=Sum('
 cost'))
 >>> qs = qs.annotate(sum_rev=Sum('rev'))
 >>> qs = qs.annotate(roi=Func(A='CAST(Sum("rev") as numeric)',
 B='CAST(Sum("cost") as numeric)',
 ...                 template='ROUND(COALESCE(%(A)s / NULLIF(%(B)s,0), 0),
 2)', output_field=FloatField()))
 >>> print qs
 DEBUG    (0.002) SELECT (TO_CHAR(ts, 'D')) AS "dow",
 SUM("testgroupby_everydaycost"."cost") AS "sum_cost",
 SUM("testgroupby_everydaycost"."rev") AS "sum_rev",
 ROUND(COALESCE(CAST(Sum("rev") as numeric) / NULLIF(CAST(Sum("cost") as
 numeric),0), 0), 2) AS "roi" FROM "testgroupby_everydaycost" GROUP BY
 (TO_CHAR(ts, 'D')) LIMIT 21; args=()
 []
 >>> print qs.query
 SELECT (TO_CHAR(ts, 'D')) AS "dow", SUM("testgroupby_everydaycost"."cost")
 AS "sum_cost", SUM("testgroupby_everydaycost"."rev") AS "sum_rev",
 ROUND(COALESCE(CAST(Sum("rev") as numeric) / NULLIF(CAST(Sum("cost") as
 numeric),0), 0), 2) AS "roi" FROM "testgroupby_everydaycost" GROUP BY
 (TO_CHAR(ts, 'D'))
 >>>
 }}}

--
Ticket URL: <https://code.djangoproject.com/ticket/24233>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.

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