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
23738	Migrations broken with django 1.7.1 when changing null from true to false.	Andrey Antukh	Markus Holtermann	"Hi!

I start having strange exceptions when I have migrated a project from django 1.7 to 1.7.1


{{{
(taiga)[3/5.0.7]{1}niwi@niwi:~/taiga/taiga-back> python manage.py sqlmigrate projects 0006
Traceback (most recent call last):
  File ""manage.py"", line 10, in <module>
    execute_from_command_line(sys.argv)
  File ""/home/niwi/.virtualenvs/taiga/lib/python3.4/site-packages/Django-1.7.2.dev20141030224451-py3.4.egg/django/core/management/__init__.py"", line 385, in execute_from_command_line
    utility.execute()
  File ""/home/niwi/.virtualenvs/taiga/lib/python3.4/site-packages/Django-1.7.2.dev20141030224451-py3.4.egg/django/core/management/__init__.py"", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File ""/home/niwi/.virtualenvs/taiga/lib/python3.4/site-packages/Django-1.7.2.dev20141030224451-py3.4.egg/django/core/management/base.py"", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File ""/home/niwi/.virtualenvs/taiga/lib/python3.4/site-packages/Django-1.7.2.dev20141030224451-py3.4.egg/django/core/management/commands/sqlmigrate.py"", line 30, in execute
    return super(Command, self).execute(*args, **options)
  File ""/home/niwi/.virtualenvs/taiga/lib/python3.4/site-packages/Django-1.7.2.dev20141030224451-py3.4.egg/django/core/management/base.py"", line 338, in execute
    output = self.handle(*args, **options)
  File ""/home/niwi/.virtualenvs/taiga/lib/python3.4/site-packages/Django-1.7.2.dev20141030224451-py3.4.egg/django/core/management/commands/sqlmigrate.py"", line 61, in handle
    sql_statements = executor.collect_sql(plan)
  File ""/home/niwi/.virtualenvs/taiga/lib/python3.4/site-packages/Django-1.7.2.dev20141030224451-py3.4.egg/django/db/migrations/executor.py"", line 77, in collect_sql
    migration.apply(project_state, schema_editor, collect_sql=True)
  File ""/home/niwi/.virtualenvs/taiga/lib/python3.4/site-packages/Django-1.7.2.dev20141030224451-py3.4.egg/django/db/migrations/migration.py"", line 108, in apply
    operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
  File ""/home/niwi/.virtualenvs/taiga/lib/python3.4/site-packages/Django-1.7.2.dev20141030224451-py3.4.egg/django/db/migrations/operations/fields.py"", line 139, in database_forwards
    schema_editor.alter_field(from_model, from_field, to_field)
  File ""/home/niwi/.virtualenvs/taiga/lib/python3.4/site-packages/Django-1.7.2.dev20141030224451-py3.4.egg/django/db/backends/schema.py"", line 473, in alter_field
    self._alter_field(model, old_field, new_field, old_type, new_type, old_db_params, new_db_params, strict)
  File ""/home/niwi/.virtualenvs/taiga/lib/python3.4/site-packages/Django-1.7.2.dev20141030224451-py3.4.egg/django/db/backends/schema.py"", line 617, in _alter_field
    sql, params = tuple(zip(*actions))
ValueError: need more than 0 values to unpack
}}}

I start research. 

Firstly I have surprised that the last created migration does not include null=False change: https://github.com/taigaio/taiga-back/blob/improvements-migrations/taiga/projects/migrations/0006_auto_20141029_1040.py but this, more surprisingly with django 1.7 emits correct sql migration without having null=False in a migration file:

{{{
(taiga)[3/5.0.7]niwi@niwi:~/taiga/taiga-back> python manage.py sqlmigrate projects 0006
BEGIN;
--
-- MIGRATION NOW PERFORMS OPERATION THAT CANNOT BE WRITTEN AS SQL:
-- Raw Python operation
--
ALTER TABLE ""projects_project"" ALTER COLUMN ""total_milestones"" SET NOT NULL;
ALTER TABLE ""projects_project"" ALTER COLUMN ""total_milestones"" DROP DEFAULT;

COMMIT;
}}}

This is a proper behavior? 

But with django 1.7.1 it seems not detects correctly the null attribute change, that causes that `actions` variable on django/db/backends/schema.py:617 to be empty, which in turn, causes that exception.

I have tried set manually the null=False parameter on the migrations file, and it no such effect (works with django 1.7 and raises exception with django 1.7.1)"	Bug	closed	Migrations	1.7	Release blocker	fixed		info+coding@…	Accepted	0	0	0	0	0	0