#35956: Add composite foreign keys
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Reporter: Csirmaz Bendegúz | Owner: (none)
Type: New feature | Status: new
Component: Database layer | Version: dev
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Csirmaz Bendegúz):
Replying to [comment:2 Mariusz Felisiak]:
> Replying to [ticket:35956 Csirmaz Bendegúz]:
> > My proposal is to add 2 parameters to `ForeignKey`: `from_fields` and
`to_fields`.
>
> Do we need these parameters? `CompositePrimaryKey` is always a primary
key so its fields should be detected automatically, IMO, the following
example should work:
> {{{#!python
> class Release(models.Model):
> pk = models.CompositePrimaryKey("version", "name")
> version = models.IntegerField()
> name = models.CharField(max_length=20)
>
>
> class RefRelease(models.Model):
> release = models.ForeignKey("Release", models.CASCADE)
> }}}
The issue with this example is `RefRelease` must have 2 fields matching
the `CompositePrimaryKey` (an `IntegerField()` and a
`CharField(max_length=20)`).
So `release` would need to create 2 fields implicitly and I'm not sure if
this would be a good direction?
We should allow sharing fields between composite foreign keys, for example
in a multitenant app, the `tenant_id` should be shared between multiple
composite foreign keys.
Let me know what you think, I'm happy to consider any alternatives.
--
Ticket URL: <https://code.djangoproject.com/ticket/35956#comment:4>
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