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
12859	Incorrect docs on Updating multiple objects at once using related records	Derek Willis	Derek Willis	"The docs for [http://docs.djangoproject.com/en/dev/topics/db/queries/#updating-multiple-objects-at-once Updating multiple objects at once] say that ""The only restriction on the QuerySet that is updated is that it can only access one database table, the model's main table. So don't try to filter based on related fields or anything like that; it won't work.""

But I've been able to update a QuerySet based on a filter of related records. You just can't ''update'' the related records. For example, given the following models:

{{{

class CoachingJob(models.Model):
    name = models.CharField(max_length=75)
    slug = models.SlugField(max_length=75)

class CollegeCoach(models.Model):
    coach = models.CharField(max_length=75)
    jobs = models.ManyToManyField(CoachingJob)
    start_date = models.DateField(null=True, blank=True)
    end_date = models.DateField(null=True, blank=True)
    is_head_coach = models.BooleanField(default=False)

}}}

I can perform the following update successfully:

{{{ 

CollegeCoach.objects.select_related().filter(jobs__name='Head Coach').update(is_head_coach=True) 

}}}

 If I try to update the CoachingJob model, it properly raises a FieldDoesNotExist error:

{{{ 

CollegeCoach.objects.select_related().filter(jobs__name='Head Coach').update(jobs__name='Top Dog')

FieldDoesNotExist: CollegeCoach has no field named 'name' 

}}}

The attached patch suggests changing the docs to say that filtering on related records is permitted, but not updating those related records, and provides an example."		closed	Documentation	1.0		fixed			Ready for checkin	1	0	0	0	0	0