#28849: SQLite foreign key constraints are not repointed on model or field
rename
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Reporter: Simon Charette | Owner: nobody
Type: Bug | Status: new
Component: Migrations | Version: 2.0
Severity: Release blocker | Keywords:
Triage Stage: Accepted | Has patch: 0
Needs documentation: 1 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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SQLite foreign key constraints are not automatically repointed on table or
column renames which is going to cause a issues to projects who previously
renamed a model or a column referenced by another model when they migrate
to Django 2.0 which start enforcing them.
e.g. of a SQLite3 session
{{{#!sql
SQLite version 3.11.0 2016-02-15 17:29:24
Enter ".help" for usage hints.
Connected to a transient in-memory database.
Use ".open FILENAME" to reopen on a persistent database.
sqlite> CREATE TABLE foo ("id" integer NOT NULL PRIMARY KEY
AUTOINCREMENT);
sqlite> CREATE TABLE bar ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT,
"foo_id" integer NOT NULL REFERENCES "foo" ("id") DEFERRABLE INITIALLY
DEFERRED);
sqlite> ALTER TABLE foo RENAME TO renamed;
sqlite> .schema bar
CREATE TABLE bar ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT,
"foo_id" integer NOT NULL REFERENCES "foo" ("id") DEFERRABLE INITIALLY
DEFERRED); # It still points to "foo"
sqlite> INSERT INTO bar (foo_id) VALUES (999);
sqlite> PRAGMA foreign_keys = ON; # From Django 2.0+
sqlite> INSERT INTO bar (foo_id) VALUES (999);
Error: no such table: main.foo
}}}
Since we're already documenting that
[https://docs.djangoproject.com/en/2.0/releases/2.0/#foreign-key-
constraints-are-now-enabled-on-sqlite users should remake their tables] it
should alleviate the issue but we should also sure to:
1. Document that tables that have been previously renamed (or had a column
referenced by a `ForeignKey(to_field)` renamed) ''must'' be rebuilt.
2. Adjust SQLite's schema editor to remake tables referencing a renamed
table or one that is remade to simulate a column rename to prevent this
from happening from now on.
This was discovered while working on fixing #25817.
--
Ticket URL: <https://code.djangoproject.com/ticket/28849>
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