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
26720	migration optimizer can produce operations that references removed models under certain circumstances	Sergey Fedoseev	Tim Graham <timograham@…>	"
{{{
class Person(models.Model):
    pass

class Book(models.Model):
    author = models.ForeignKey(Person)
}}}

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

class Book(models.Model):
    author = models.ForeignKey(Person)

class Reviewer(models.Model):
    pass

class Review(models.Model):
    book = models.ForeignKey(Book)
}}}

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

class Reviewer(models.Model):
    pass

class Review(models.Model):
    reviewer = models.ForeignKey(Reviewer)
    book = models.ForeignKey(Book)
}}}


{{{
$ python manage.py squashmigrations test_app 0003
$ python manage.py migrate test_app
Applying test_app.0001_squashed_0003_auto_20160607_1120...Traceback (most recent call last):
  File ""manage.py"", line 22, in <module>
    execute_from_command_line(sys.argv)
  File ""/home/sergey/dev/django/django/core/management/__init__.py"", line 354, in execute_from_command_line
    utility.execute()
  File ""/home/sergey/dev/django/django/core/management/__init__.py"", line 346, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File ""/home/sergey/dev/django/django/core/management/base.py"", line 394, in run_from_argv
    self.execute(*args, **cmd_options)
  File ""/home/sergey/dev/django/django/core/management/base.py"", line 445, in execute
    output = self.handle(*args, **options)
  File ""/home/sergey/dev/django/django/core/management/commands/migrate.py"", line 222, in handle
    executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
  File ""/home/sergey/dev/django/django/db/migrations/executor.py"", line 110, in migrate
    self.apply_migration(states[migration], migration, fake=fake, fake_initial=fake_initial)
  File ""/home/sergey/dev/django/django/db/migrations/executor.py"", line 148, in apply_migration
    state = migration.apply(state, schema_editor)
  File ""/home/sergey/dev/django/django/db/migrations/migration.py"", line 115, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File ""/home/sergey/dev/django/django/db/migrations/operations/models.py"", line 59, in database_forwards
    schema_editor.create_model(model)
  File ""/home/sergey/dev/django/django/db/backends/base/schema.py"", line 236, in create_model
    definition, extra_params = self.column_sql(model, field)
  File ""/home/sergey/dev/django/django/db/backends/base/schema.py"", line 135, in column_sql
    db_params = field.db_parameters(connection=self.connection)
  File ""/home/sergey/dev/django/django/db/models/fields/related.py"", line 2010, in db_parameters
    return {""type"": self.db_type(connection), ""check"": []}
  File ""/home/sergey/dev/django/django/db/models/fields/related.py"", line 2001, in db_type
    rel_field = self.related_field
  File ""/home/sergey/dev/django/django/db/models/fields/related.py"", line 1904, in related_field
    return self.foreign_related_fields[0]
  File ""/home/sergey/dev/django/django/db/models/fields/related.py"", line 1638, in foreign_related_fields
    return tuple(rhs_field for lhs_field, rhs_field in self.related_fields if rhs_field)
  File ""/home/sergey/dev/django/django/db/models/fields/related.py"", line 1625, in related_fields
    self._related_fields = self.resolve_related_fields()
  File ""/home/sergey/dev/django/django/db/models/fields/related.py"", line 1610, in resolve_related_fields
    raise ValueError('Related model %r cannot be resolved' % self.rel.to)
ValueError: Related model u'test_app.Person' cannot be resolved
}}}
 "	Bug	closed	Migrations	dev	Normal	fixed			Accepted	1	0	0	1	0	0