Incorrect primary key detection in complex model relationships

[DrMeers@…]

Hard to explain in a sentence; here is a simplified example:

demo/models.py:

rom django.db import models

class RelatableContent(models.Model):
   related_items = models.ManyToManyField('RelatableContent', symmetrical=True)


class WikiPage(RelatableContent):
   parent = models.ForeignKey('self')
   
   class Meta:
      abstract = True


class MyWiki(WikiPage):
   pass

Create migration:

$ ./manage.py schemamigration --initial demo
Creating migrations directory at '.../demo/migrations'...
Creating __init__.py in '.../demo/migrations'...
 + Added model demo.RelatableContent
 + Added M2M table for related_items on demo.RelatableContent
 + Added model demo.MyWiki
Created 0001_initial.py. You can now apply this migration with: ./manage.py migrate demo

Run migration:

./manage.py migrate demo
Running migrations for demo:
 - Migrating forwards to 0001_initial.
 > demo:0001_initial
Traceback (most recent call last):
...
django.db.utils.DatabaseError: column "id" referenced in foreign key constraint does not exist

Problem SQL statement:

ALTER TABLE "demo_mywiki" ADD CONSTRAINT "parent_id_refs_id_2d9983b3" FOREIGN KEY ("parent_id") REFERENCES "demo_mywiki" ("id") DEFERRABLE INITIALLY DEFERRED; 

Desired output:

$ ./manage.py sqlall demo
BEGIN;
CREATE TABLE "demo_relatablecontent_related_items" (
    "id" serial NOT NULL PRIMARY KEY,
    "from_relatablecontent_id" integer NOT NULL,
    "to_relatablecontent_id" integer NOT NULL,
    UNIQUE ("from_relatablecontent_id", "to_relatablecontent_id")
)
;
CREATE TABLE "demo_relatablecontent" (
    "id" serial NOT NULL PRIMARY KEY
)
;
ALTER TABLE "demo_relatablecontent_related_items" ADD CONSTRAINT "from_relatablecontent_id_refs_id_19b1eb18" FOREIGN KEY ("from_relatablecontent_id") REFERENCES "demo_relatablecontent" ("id") DEFERRABLE INITIALLY DEFERRED;
ALTER TABLE "demo_relatablecontent_related_items" ADD CONSTRAINT "to_relatablecontent_id_refs_id_19b1eb18" FOREIGN KEY ("to_relatablecontent_id") REFERENCES "demo_relatablecontent" ("id") DEFERRABLE INITIALLY DEFERRED;
CREATE TABLE "demo_mywiki" (
    "relatablecontent_ptr_id" integer NOT NULL UNIQUE REFERENCES "demo_relatablecontent" ("id") DEFERRABLE INITIALLY DEFERRED,
    "parent_id" integer NOT NULL
)
;
ALTER TABLE "demo_mywiki" ADD CONSTRAINT "parent_id_refs_relatablecontent_ptr_id_2d9983b3" FOREIGN KEY ("parent_id") REFERENCES "demo_mywiki" ("relatablecontent_ptr_id") DEFERRABLE INITIALLY DEFERRED;
CREATE INDEX "demo_mywiki_parent_id" ON "demo_mywiki" ("parent_id");
COMMIT;

Using PostgreSQL.

[andrew]

Hm, that seems possible. I'll put it on the list of things to fix...

[Aram Dulyan <aram00@…>]

Workaround Django bug #13987

[Aram Dulyan <aram00@…>]

This issue stems from ​Django bug #13987 (see link for more details). I've attached a diff that provides a future-safe workaround for this problem (tests pass).

[andrew]

Thanks, looks good. Committed as [5fe9e105acf3].