Currently trying to grab an average of a sum of a group by, but when I try to execute the correct queryset it complains of incorrect syntax
objs = MyModel.objects.filter(...).values('user', 'value')
objs = objs.annotate(sum=Sum('value'))
# i've also tried adding `.values('sum')` to the above
objs = objs.aggregate(Avg('sum')) # whines here
Is there any way to do this without dropping in SQL? The desired SQL is along the lines of
SELECT AVG(`sum`) as `avg` FROM (
SELECT SUM(`appname_mymodel`.`value`) AS `sum`
FROM `appname_mymodel`
GROUP BY
`appname_mymodel`.`user_id`, `appname_mymodel`.`value`
) as subquery ORDER BY NULL;
Not sure if django plays well with subqueries.
Here is the error message:
ProgrammingError: (1064, "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FROM (SELECT SUM(`appname_mymodel`.`value`) AS `sum` FROM `appname_' at line 1")
Django version - 1.6.5
MySQL version - 5.5
Notes:
- If I leave off the
values(the group by), it works fine (i.e.objs.filter(...).annotate(...).aggregate(...) - The example below is sufficient as a fully reproducible example.
Model:
# Create your models here.
class UserProfile(models.Model):
name = models.CharField(max_length=200)
class OtherFK(models.Model):
name = models.CharField(max_length=200)
class MyModel(models.Model):
# Happens if value is CharField or IntegerField
value = models.CharField(max_length=200, blank=True, null=True)
date = models.DateField()
user = models.ForeignKey(UserProfile)
other_fk = models.ForeignKey(OtherFK)
Example:
>>> from app_name.models import UserProfile, OtherFK, MyModel
>>> up = UserProfile.objects.create(name="test")
>>> fk = OtherFK.objects.create(name="test")
>>> v1 = MyModel.objects.create(user=up, other_fk=fk, value="12", date="2015-10-01")
>>> v2 = MyModel.objects.create(user=up, other_fk=fk, value="13", date="2015-10-02")
>>> from django.db.models import Sum,Avg
>>> MyModel.objects.all().values("user").distinct().annotate(sum=Sum("value")).aggregate(Avg('sum'))
ProgrammingError: (1064, "You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FROM (SELECT DISTINCT `app_name_mymodel`.`user_id` AS `user_id`, SUM(`app_name_m' at line 1")
>>> MyModel.objects.all().values("user").distinct().annotate(sum=Sum("value"))
[{'sum': 25.0, 'user': 1L}]
>>> print MyModel.objects.all().values("user").distinct().annotate(sum=Sum("value")).query
SELECT DISTINCT `app_name_mymodel`.`user_id`, SUM(`app_name_mymodel`.`value`) AS `sum` FROM `app_name_mymodel` GROUP BY `app_name_mymodel`.`user_id` ORDER BY NULL
