[Django] #22659: parent_link relationships ignored by migrations

[Django]

#22659: parent_link relationships ignored by migrations
---------------------------------+------------------------
     Reporter:  tbartelmess      |      Owner:  nobody
         Type:  Bug              |     Status:  new
    Component:  Migrations       |    Version:  1.7-beta-2
     Severity:  Release blocker  |   Keywords:
 Triage Stage:  Unreviewed       |  Has patch:  0
Easy pickings:  0                |      UI/UX:  0
---------------------------------+------------------------
 The parent_link property on OneToOne relationships is ignored by the
 migration system. This causes the database to end up with two parent
 relationships.

 For example if you have a model like this:

 {{{
 class Company(models.Model):
     name = models.CharField(max_length=100)

 class FooCompany(Company):
     parent_company = models.OneToOneField(Company, primary_key = True,
 parent_link=True)
 }}}

 without migrations the generated tables are correct


 {{{
 BEGIN;
 CREATE TABLE "foo_company" (
     "id" integer NOT NULL PRIMARY KEY AUTOINCREMENT,
     "name" varchar(100) NOT NULL
 )
 ;
 CREATE TABLE "foo_foocompany" (
     "parent_company_id" integer NOT NULL PRIMARY KEY REFERENCES
 "foo_company" ("id")
 )
 ;

 COMMIT;
 }}}

 the migration system however ignores that there is a parent link set and
 generate the tables like this

 {{{
 CREATE TABLE "foo_company" (
     "id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, "name" varchar(100)
 NOT NULL
 );

 CREATE TABLE "foo_foocompany" (
     "company_ptr_id" integer NOT NULL UNIQUE REFERENCES "foo_company"
 ("id"),
     "parent_company_id" integer NOT NULL PRIMARY KEY REFERENCES
 "foo_company" ("id")
 );
 }}}

 I've categorized this as a blocker, because it makes parent_links
 unusable, since the ORM won't know about the additional 'company_ptr_id'
 column causing inserts to fail because of the NOT NULL violation on that
 column

-- 
Ticket URL: <https://code.djangoproject.com/ticket/22659>
Django <https://code.djangoproject.com/>
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