Question

I’m getting the following error when I run ./manage.py reset app1:

Error: Error: app1 couldn't be reset. Possible reasons:
  * The database isn't running or isn't configured correctly.
  * At least one of the database tables doesn't exist.
  * The SQL was invalid.
Hint: Look at the output of 'django-admin.py sqlreset app2'. That's the SQL this command     wasn't able to run.
The full error: (1217, 'Cannot delete or update a parent row: a foreign key constraint fails')

with a model which has OneToOneField with another model in a different app (let’s say app2). I’m using MySQL InnoDB. More accurately, OneToOneField is declared in app2’s model.

How do I get rid of this error?

Update:
The output of sqlreset command is:

(app1)

BEGIN;
DROP TABLE `app1_instance`;
DROP TABLE `app1_instancegroup`;
CREATE TABLE `app1_instancegroup` (
    `id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
    -- some more fields
)
;
CREATE TABLE `app1_instance` (
    `id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
    `belongs_to_id` integer NOT NULL,
    -- some more fields
)
;
ALTER TABLE `app1_instance` ADD CONSTRAINT `belongs_to_id_refs_id_455b868f` FOREIGN KEY (`belongs_to_id`) REFERENCES `app1_instancegroup` (`id`);
CREATE INDEX `app1_instance_belongs_to_id` ON `app1_instance` (`belongs_to_id`);
COMMIT;

(app2)

BEGIN;
DROP TABLE `app2_team`;
CREATE TABLE `app2_team` (
    `id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
    `instance_group_id` integer NOT NULL UNIQUE,
    -- some more fields
)
;
ALTER TABLE `app2_team` ADD CONSTRAINT `instance_group_id_refs_id_39493b52` FOREIGN KEY (`instance_group_id`) REFERENCES `app1_instancegroup` (`id`);
COMMIT;

Answer 1

One step that can make manually resetting easier is (and avoid the dread ERROR 1217):

SET foreign_key_checks = 0

From http://dev.mysql.com/doc/refman/5.1/en/innodb-foreign-key-constraints.html:

InnoDB does not allow you to drop a
table that is referenced by a FOREIGN
KEY constraint, unless you do SET
foreign_key_checks = 0. When you drop
a table, the constraints that were
defined in its create statement are
also dropped.