Re: Two way many-to-many relationships

On Sunday, March 27, 2011 02:32:15 pm Dilan wrote:
> Hi All,
>
> I'm working on a model similar to
> http://docs.djangoproject.com/en/1.3/topics/db/models/#extra-fields-on-many
> -to-many-relationships .
>
> Say, I need to add the field, groups = models.ManyToManyField(Group,
> through='Membership') to Person class
>
> Two questions:
> 1. In Django, is this allowed?

Yes. But you'll want to have a unique related_name also, iirc.

> 2. In Python, how do you forward declare Group class for this code to
> work?
>

This isn't really a python way but a django way [1]

ManyToManyField('Group', ...)

In python you can't forward declare outside of the module the object is in.
there is no equivalent to Class Test; as in c++. (you can dynamically import
with the imp module though but this isn't forward declaring).

Django models load in such a way that it doesn't know modules that come after
it in the same module/file and this was to address that.

scroll down just a tad on the link below to get info on the related_name
attribute.

HTH,

Mike

[1] http://docs.djangoproject.com/en/1.3/ref/models/fields/#lazy-relationships
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