On Fri, Apr 12, 2013 at 07:35:45AM -0700, Anssi Kääriäinen wrote: > On 12 huhti, 16:44, Michal Petrucha <michal.petru...@ksp.sk> wrote: > ForeignKeys have been changed a lot since 2012-11-04. The introduction > of ForeignObject (which is base for ForeignKey) means that there is > support for multicolumn joins in the ORM now, and that ForeignObject > itself is a non-concrete field (not in ._meta.virtual_fields though). > ForeignObject currently works only on ORM level, so there is no API > for creating multicolumn foreign keys. > > In any case, the GSoC proposal should take the introduction of > ForeignObject in account. tests/foreign_object contain some examples > related to ForeignObject functionality, exploring how those examples > work is a good idea.
This has been on my TODO list for a few days actually, I was going
through the work done regarding #19385 [1] and noticed this. However,
I still need to give it a more thorough examination to fully get a
grasp on this.
> Another big issue to solve is how to store the fields in model._meta.
> IMO a good idea is to add all fields into some attribute ('all_fields'
> as name might be good...), then separate the fields for different use
> cases based on features the fields has. For example concrete_fields is
> [f for f in self.all_fields if f.column], form fields are [f for f in
> self.all_fields if f.form_field] (or maybe this should be called
> logical fields - a multicolumn foreign key is logical, but not
> concrete field, and the fields used by the foreign key are concrete
> but not logical fields). The different field lists can be
> cached_properties so there will be no problems from performance
> perspective.
As a matter of fact, this is one of the first things I did back in
2011. (-: Almost exactly like that -- _meta.fields contains all fields
(except for M2M), _meta.concrete_fields, _meta.virtual_fields and I
think I also needed a _meta.local_concrete (for non-inherited fields;
I couldn't find a better name for it that wouldn't be too verbose).
[1] https://code.djangoproject.com/ticket/19385
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