multiple manytomanyfield on self causes complaint in manage.py
|Reported by:||Owned by:||Russell Keith-Magee|
|Has patch:||no||Needs documentation:||no|
|Needs tests:||no||Patch needs improvement:||no|
class Foo(models.Model): related = models.ManyToManyField('self') suggestions = models.ManyToManyField('self')
Both relations should be symmetrical. If A suggests B, B suggests A (for this code
What I expected to happen is adding B to A would add A to B. Instead I get:
app.foo: Accessor for m2m field 'menu_suggestions' clashes with related
m2m field 'Foo.foo_set'. Add a related_name argument to the definition
app.foo: Accessor for m2m field 'related' clashes with related m2m field
'Foo.foo_set'. Add a related_name argument to the definition for 'related'.
Doesn't matter whether I set symmetrical to false or true.
The confusion stems from model-api.txt which states:
``symmetrical`` Only used in the definition of ManyToManyFields on self. Consider the following model: class Person(models.Model): friends = models.ManyToManyField("self") When Django processes this model, it identifies that it has a ``ManyToManyField`` on itself, and as a result, it doesn't add a ``person_set`` attribute to the ``Person`` class. Instead, the ``ManyToManyField`` is assumed to be symmetrical -- that is, if I am your friend, then you are my friend. If you do not want symmetry in ``ManyToMany`` relationships with ``self``, set ``symmetrical`` to ``False``. This will force Django to add the descriptor for the reverse relationship, allowing ``ManyToMany`` relationships to be non-symmetrical.