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
29058	Adding 'null=True' to a PointField doesn't create working migration	Yaman Ozakin	Victor Munene	"before:

{{{
class House(models.Model):
  point = models.PointField()
}}}

after:

{{{
class House(models.Model):
  point = models.PointField(null=True)
}}}

migration:
{{{
class Migration(migrations.Migration):

    dependencies = [
        ('myapp', '0001_initial'),
    ]

    operations = [
        migrations.AlterField(
            model_name='house',
            name='point',
            field=django.contrib.gis.db.models.fields.PointField(null=True, srid=4326),
        ),
    ]
}}}

Traceback:

{{{
python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, myapp, sessions
Running migrations:
  Applying myapp.0002_auto_20180125_1119...Traceback (most recent call last):
  File ""manage.py"", line 22, in <module>
    execute_from_command_line(sys.argv)
  File ""/Users/Basia/yamyam/research/django/myenv/lib/python3.6/site-packages/django/core/management/__init__.py"", line 364, in execute_from_command_line
    utility.execute()
  File ""/Users/Basia/yamyam/research/django/myenv/lib/python3.6/site-packages/django/core/management/__init__.py"", line 356, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File ""/Users/Basia/yamyam/research/django/myenv/lib/python3.6/site-packages/django/core/management/base.py"", line 283, in run_from_argv
    self.execute(*args, **cmd_options)
  File ""/Users/Basia/yamyam/research/django/myenv/lib/python3.6/site-packages/django/core/management/base.py"", line 330, in execute
    output = self.handle(*args, **options)
  File ""/Users/Basia/yamyam/research/django/myenv/lib/python3.6/site-packages/django/core/management/commands/migrate.py"", line 204, in handle
    fake_initial=fake_initial,
  File ""/Users/Basia/yamyam/research/django/myenv/lib/python3.6/site-packages/django/db/migrations/executor.py"", line 115, in migrate
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
  File ""/Users/Basia/yamyam/research/django/myenv/lib/python3.6/site-packages/django/db/migrations/executor.py"", line 145, in _migrate_all_forwards
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
  File ""/Users/Basia/yamyam/research/django/myenv/lib/python3.6/site-packages/django/db/migrations/executor.py"", line 244, in apply_migration
    state = migration.apply(state, schema_editor)
  File ""/Users/Basia/yamyam/research/django/myenv/lib/python3.6/site-packages/django/db/migrations/migration.py"", line 129, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File ""/Users/Basia/yamyam/research/django/myenv/lib/python3.6/site-packages/django/db/migrations/operations/fields.py"", line 216, in database_forwards
    schema_editor.alter_field(from_model, from_field, to_field)
  File ""/Users/Basia/yamyam/research/django/myenv/lib/python3.6/site-packages/django/db/backends/base/schema.py"", line 494, in alter_field
    (old_field, new_field),
ValueError: Cannot alter field myapp.House.point into myapp.House.point - they do not properly define db_type (are you using a badly-written custom field?)
}}}

Using Spatialite as backend engine."	Bug	assigned	GIS	dev	Normal		geodjango, pointfield		Accepted	1	0	0	1	0	0