#28563: Allow parent relations to specify the related_name of a class property
--------------------------------+--------------------------------------
Reporter: Samuel Spencer | Owner: tothegump
Type: New feature | Status: closed
Component: Uncategorized | Version: 1.11
Severity: Normal | Resolution: wontfix
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
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Description changed by Samuel Spencer:
Old description:
> I can't come up with an appropriate example, so I'll use a cut back
> version of actual code. I'm trying to implement an ISO standard, and am
> using a concrete base class, with a number of relations between objects,
> as shown below. Unfortunately, the names of these objects and relations
> are defined by the spec and can't be changed without a lot of hassle.
>
> {{{
>
> class Metadata(models.Model):
> name = models.CharField(max_length=255)
>
> class Property(Metadata):
> pass
>
> class ObjectClass(Metadata):
> pass
>
> class DataElementConcept(Metadata):
> object_class = models.ForeignKey(ObjectClass)
> property= models.ForeignKey(Property)
>
> }}}
>
> However, the system checker has a problem with this:
>
> {{{
> SystemCheckError: System check identified some issues:
>
> ERRORS:
> aristotle_mdr.DataElementConcept.property: (models.E006) The field
> 'property' clashes with the field 'property' from model
> 'aristotle_mdr._concept'.
> }}}
>
> What appears to happen is that DataElementConcept.property (a relation
> between two pieces of metadata) is clashing with MetadataItem.property (a
> relation from parent class to child class).
>
> Since a parent-child relationship using inheritance is just a
> OneToOneField thats made by
> [https://github.com/django/django/blob/5cc746206726c538c36a2830e7c068f1c8a0e7c8/django/db/models/base.py#L234
> django.db.models.base.ModelBase] it'd be nice to be able to add some
> details to a classes Meta field to change the related_name of the
> generated field, for example:
>
> {{{
>
> class Metadata(models.Model):
> name = models.CharField(max_length=255)
>
> class Property(Metadata):
> class Meta:
> parent_related_name = "property_subclass"
>
> }}}
>
> and the ModelBase coude would be similar to:
>
> {{{
> field = OneToOneField(
> base,
> on_delete=CASCADE,
> name=attr_name,
> auto_created=True,
> parent_link=True,
> related_name=base._meta.parent_related_name
> )
> }}}
New description:
I didn't even realise that was possible! Cheers.
--
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Ticket URL: <https://code.djangoproject.com/ticket/28563#comment:4>
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