[Django] #28563: Allow parent relations to specify the related_name of a class property
Django
------------------------------------------+------------------------
Reporter: Samuel Spencer | Owner: nobody
Type: New feature | Status: new
Component: Uncategorized | Version: 1.11
Severity: Normal | 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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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
)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/28563>
Django <https://code.djangoproject.com/>
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Django
Reporter: Samuel Spencer | Owner: nobody
Type: New feature | Status: new
Component: Uncategorized | Version: 1.11
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
Comment (by Simon Charette):
I'm not convinced it's worth adding a `Meta` option for the rare cases
when this is required. Explicitly defining your parent link as you've
pointed out should do.
{{{#!python
class Property(Metadata):
metadata_ptr = OneToOneField(
Metadata,
on_delete=CASCADE,
parent_link=True,
related_name='property_subclass',
)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/28563#comment:1>
Django
Reporter: Samuel Spencer | Owner: tothegump
Type: New feature | Status: assigned
Component: Uncategorized | Version: 1.11
Severity: Normal | Resolution:
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
Changes (by tothegump):
* owner: nobody => tothegump
* status: new => assigned
--
Ticket URL: <https://code.djangoproject.com/ticket/28563#comment:2>
Django
Reporter: Samuel Spencer | Owner: tothegump
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
Changes (by Tim Graham):
* status: assigned => closed
* resolution: => wontfix
Comment:
Agreed, I think defining fields is a more clear solution than a `Meta`
option.
--
Ticket URL: <https://code.djangoproject.com/ticket/28563#comment:3>
Django
Reporter: Samuel Spencer | Owner: tothegump
Type: New feature | Status: closed
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
Description changed by Samuel Spencer:
Old description:
New description:
I didn't even realise that was possible! Cheers.
--
--
Ticket URL: <https://code.djangoproject.com/ticket/28563#comment:4>
Django
Reporter: Samuel Spencer | Owner: tothegump
Type: New feature | Status: closed
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
Old description:
> I didn't even realise that was possible! Cheers.
New description:
{{{
class Property(Metadata):
pass
class ObjectClass(Metadata):
pass
}}}
{{{
}}}
--
Comment (by Samuel Spencer):
I didn't even realise that was possible! Cheers.
--
Ticket URL: <https://code.djangoproject.com/ticket/28563#comment:5>