filter

[Ales Zoulek <ales.zoulek@…>]

When using OR operation on two Q objects, witch are both filtering on the same table, it leaves out one condition in WHERE clause.

Given this model and the filter, django will query database for:

SELECT "a_team"."id", "a_team"."name" FROM "a_team" 
   LEFT OUTER JOIN "a_match" ON ("a_team"."id" = "a_match"."home_team_id")
   LEFT OUTER JOIN "a_match" T4 ON ("a_team"."id" = T4."guest_team_id")
   WHERE "a_match"."round_id" = 1;

But it should use:

SELECT "a_team"."id", "a_team"."name" FROM "a_team" 
   LEFT OUTER JOIN "a_match" ON ("a_team"."id" = "a_match"."home_team_id")
   LEFT OUTER JOIN "a_match" T4 ON ("a_team"."id" = T4."guest_team_id")
   WHERE "a_match"."round_id" = 1 OR T4.round_id = 1;

Mind the difference in the where clause. Even though T4 is just alias for 'a_match' table, and both conditions are comparing 'round_id' for the same value (1), it's important to use both.

from django.db import models

class Team(models.Model):
    name = models.CharField(max_length=100)

class Round(models.Model):
    name = models.CharField(max_length=100)

class Match(models.Model):
    home_team = models.ForeignKey(Team, related_name='home_team_set')
    guest_team = models.ForeignKey(Team, related_name='guest_team_set')
    round = models.ForeignKey(Round)

__test__ = {'bug': """
# Data init
>>> r = Round(name='round 1')
>>> r.save()
>>> t1 = Team(name='Cze')
>>> t1.save()
>>> t2 = Team(name='USA')
>>> t2.save()
>>> Match(home_team=t1, guest_team=t2, round=r).save()


# Get teams with matches in round 'r'
>>> result = Team.objects.filter(models.Q(home_team_set__round=r) | models.Q(guest_team_set__round=r))
>>> len(result)
2


"""}

[jbronn]

I think this is the same is #7125.

[Jacob]

Indeed; another dup of #7125.