Re: First models.py needs tuning

On Tue, Apr 18, 2017 at 03:13:24PM -0700, Rich Shepard wrote:
> Converting from the postgres schema to a Django models.py for my first
> Django project. Most of the syntax (64 lines in the file) should be correct,
> but there are two conditions that I have not found how to handle.
>
> First, a couple of classes have primary keys with three fields. I know
> there's a models.PrimaryKey but haven't found an example of how to apply
> that to a field that foreign key fields.

I have bad news for you – Django does not at this point in time have
support for multi-column primary keys. A large part of the ORM is
built around the assumption that each model instance is identified by
a single field acting as its primary key.

A lot of time and effort has been spent trying to implement them, but
it's a huge project, and it's not even close to being ready to get
merged. As far as I know, nobody is currently even actively working on
this feature. If you're interested, look up composite fields in the
archives of django-developers@.

For the foreseeable future, though, I'd strongly recommend that you
save yourself a lot of trouble, and just add a surrogate primary key
field to all your tables and models.

Cheers,

Michal

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