#24317: Deprecate field.rel, replace it with real field instances
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Reporter: akaariai | Owner: nobody
Type: | Status: new
Cleanup/optimization |
Component: Database | Version: master
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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The problem is that when using get_fields(), you'll get either a field.rel
instance (for reverse side of user defined fields), or a real field
instance (for example ForeignKey). These behave differently, so that the
user must always remember which one he is dealing with. This creates lots
of non-necessary conditioning in multiple places of Django.
For example, the select_related descent has one branch for descending
foreign keys and one to one fields, and another branch for descending to
reverse one to one fields. Conceptually both one to one and reverse one to
one fields are very similar, so this complication is non-necessary.
The idea is to deprecate field.rel, and instead add field.remote_field.
The remote_field is just a field subclass, just like everything else in
Django.
The benefits are:
- Conceptual simplicity - dealing with fields and rels is non-necessary,
and confusing. Everything from get_fields() should be a field.
- Code simplicity - no special casing based on if a given relation is
described by a rel or not
- Code reuse - ReverseManyToManyField is in most regard exactly like
ManyToManyField
The expected problems are mostly from 3rd party code. Users of _meta that
already work on expectation of getting rel instances will likely need
updating. Those users who subclass Django's fields (or duck-type Django's
fields) will need updating. Examples of such projects include django-rest-
framework and django-taggit.
Very work-in-progress code available from
https://github.com/akaariai/django/tree/virtual_rel_field
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Ticket URL: <https://code.djangoproject.com/ticket/24317>
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