Summary: django should throw an exception when a model has its own
name as the 'to' field of a ManyToMany() insead of 'self'.
I had a field like this:
def Item(Model):
name = CharField(max_length=100)
related_items = ManyToManyField('Item', blank=True)
But this caused some very strange bugs. For example:
item1 = Item.objects.create(name='First')
item1.save()
item2 = Item.objects.create(name='Second', related_items=[item1])
item2.save()
print item2.related_items
> []
print len(item2.related_items)
> 0
The correct way, as stated in the docs, is to use 'self' for a
recursive relationship.
def Item(Model):
name = CharField(max_length=100)
related_items = ManyToManyField('self', blank=True)
(NOTE: This is pseudo/test code, may contain typos)
When I use this method, it works fine. However, if the first method
is incorrect and produces functionally invalid results, then there
should be a model validation check for this and an exception if it's
found. Basically, if a model has a ManyToManyField() with its own
name as the 'to' parameter, an exception should be raised.
I understsand that the current functoinality & docs are working as
they're supposed to. However, it would also be nice for django to
raies an exception instead of silently failing and producing invalid
results.
Have I missed anything? I may be misunderstanding the problem here,
but I have managed to fix my problem and figure this could save others
from the same trap. I'd like to get some input before submitting a
ticket.
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