#35129: Support customize ForeignKey DDL when db_constraint=False
-------------------------------------+-------------------------------------
Reporter: elonzh | Owner: nobody
Type: Uncategorized | Status: closed
Component: Database layer | Version: 5.0
(models, ORM) |
Severity: Normal | Resolution: invalid
Keywords: | Triage Stage:
| Unreviewed
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 Simon Charette):
I think this will eventually come in a form or the other eventually
through a `Relation` object
[http://charettes.name/djangoconus2022/slides.html#39 that can be defined
at the model level] but in the mean time your best bet is to use (at your
own risks) the undocumented `django.db.models.ForeignObject` object to
define such relationships.
{{{#!python
class Journal(Model):
issn = models.CharField(max_length=9, primary_key=True)
name = models.CharField(max_length=255)
class Biblio(Model):
issn = models.CharField(max_length=50, default="", blank=True)
journal = models.ForeignObject(
Journal,
models.DO_NOTHING,
from_fields=["issn"],
to_fields=["issn"],
)
}}}
Under the hood `ForeignKey` is `Field` + `ForeignObject` + the equivalent
of a `ForeignKeyConstraint(ForeignObject)` entry in
`Model._meta.constraints` so if you care about the ORM + JOIN generation
part and don't want a database constraint it's likely what you're looking
for.
--
Ticket URL: <https://code.djangoproject.com/ticket/35129#comment:4>
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