id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
26088	Changing a proxy model to multi-table inheritance does not modify FKs of the model	Jon Dufresne	nobody	"Original {{{models.py}}}:

{{{
class MyBaseModel(models.Model):
    pass

class MyModel(MyBaseModel):
    class Meta:
        proxy = True

class MyOtherModel(models.Model):
    my_model = models.ForeignKey(MyModel)
}}}

The initial migration creates the expected FK (full migration {{{0001_initial.py}}} below): {{{""myapp_myothermodel_my_model_id_cce558da_fk_myapp_mybasemodel_id"" FOREIGN KEY (my_model_id) REFERENCES myapp_mybasemodel(id) DEFERRABLE INITIALLY DEFERRED}}}.

Later, I may decide to use multi-table inheritance. To do so,  I would remove the `proxy = True` from {{{MyModel}}}. After running {{{makemigrations}}}, the new migration creates the new table, but does not adjust the existing FK. (full migration {{{0002_auto.py}}} below.)

If I had used multi-table inheritance from the start, the initial migration would have created the correct FK as expected. The end results is that these identically defined models have different database schema.

The fact that this FK is pointing to the incorrect table and field could potentially break data integrity checks and expectations as the FK is not verified against the correct model/table.

{{{0001_initial.py}}}
{{{
# -*- coding: utf-8 -*-
# Generated by Django 1.10.dev20160115013918 on 2016-01-15 01:39
from __future__ import unicode_literals

from django.db import migrations, models
import django.db.models.deletion


class Migration(migrations.Migration):

    initial = True

    dependencies = [
    ]

    operations = [
        migrations.CreateModel(
            name='MyBaseModel',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
            ],
        ),
        migrations.CreateModel(
            name='MyOtherModel',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
            ],
        ),
        migrations.CreateModel(
            name='MyModel',
            fields=[
            ],
            options={
                'proxy': True,
            },
            bases=('myapp.mybasemodel',),
        ),
        migrations.AddField(
            model_name='myothermodel',
            name='my_model',
            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='myapp.MyModel'),
        ),
    ]
}}}

{{{0002_auto.py}}}
{{{
# -*- coding: utf-8 -*-
# Generated by Django 1.10.dev20160115014052 on 2016-01-15 01:41
from __future__ import unicode_literals

from django.db import migrations, models
import django.db.models.deletion


class Migration(migrations.Migration):

    dependencies = [
        ('myapp', '0001_initial'),
    ]

    operations = [
        migrations.DeleteModel(
            name='MyModel',
        ),
        migrations.CreateModel(
            name='MyModel',
            fields=[
                ('mybasemodel_ptr', models.OneToOneField(auto_created=True, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='myapp.MyBaseModel')),
            ],
            bases=('myapp.mybasemodel',),
        ),
    ]
}}}

(All tests ran using master branch of Django with PostgreSQL backend.)"	Bug	closed	Migrations	dev	Normal	fixed			Accepted	1	0	0	0	0	0