Hi developers - your review would be appreciated here!
It seems to me, based on my experimentation, that if I have an
intermediary model that has a many-to-many relationship from the model
to itself, that the order of the two fields that point back to the
model is important. For example:
class Task(models.Model):
child_tasks = models.ManyToManyField('self', null=True,
blank=True, through='Membership', symmetrical=False,
related_name="parent_tasks")
class Membership(models.Model):
parent_task = models.ForeignKey(Task,
related_name='parent_memberships')
child_task = models.ForeignKey(Task,
related_name='child_memberships')
percentage = models.DecimalField(default=0, max_digits=5,
decimal_places=2)
Assuming I have my models defined as above, then if I do:
Task.objects.filter(subtasks__isnull=False)
Then I get a select that looks like this:
select <columns> from taskmanager_task INNER JOIN
taskmanager_membership ON (taskmanager_task.id =
taskmanager_membership.parent_task_id)
However, if I change the order of parent_task and child_task in the
Membership class (ie, make child_task first), then the select is
different:
select <columns> from taskmanager_task INNER JOIN
taskmanager_membership ON (taskmanager_task.id =
taskmanager_membership.child_task_id)
The doc does not really describe this, as far as I can see.
Developers - is this something I should post as a bug ticket or am I
missing something? The doc does say that the two foreign keys will be
treated as the two (different) sides of the many-to-many relation, so
I have a feeling this is an attempt to touch on this point.
Anyway, just trying to confirm that this is expected behavior and
whether it would be worthwhile for me to post a bug ticket on it for
better doc.
Thanks!
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