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
23902	Migrating between Geography / Geometry types fails	mitchell	Jon Culver	"Adding or removing the ""{{{geography=True}}}"" argument to or from a GIS column generates a migration which then fails to run because the columns are two distinct types and cannot be converted between easily.

Exception:
{{{
Traceback (most recent call last):
  File ""bin/django"", line 9, in <module>
    load_entry_point('myproject==1.0.0', 'console_scripts', 'django')()
  File ""/home/mitchell/myproject/myproject/manage.py"", line 19, in main
    execute_from_command_line(argv)
  File ""/home/mitchell/myproject/local/lib/python2.7/site-packages/django/core/management/__init__.py"", line 385, in execute_from_command_line
    utility.execute()
  File ""/home/mitchell/myproject/local/lib/python2.7/site-packages/django/core/management/__init__.py"", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File ""/home/mitchell/myproject/local/lib/python2.7/site-packages/django/core/management/base.py"", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File ""/home/mitchell/myproject/local/lib/python2.7/site-packages/django/core/management/base.py"", line 338, in execute
    output = self.handle(*args, **options)
  File ""/home/mitchell/myproject/local/lib/python2.7/site-packages/django/core/management/commands/migrate.py"", line 160, in handle
    executor.migrate(targets, plan, fake=options.get(""fake"", False))
  File ""/home/mitchell/myproject/local/lib/python2.7/site-packages/django/db/migrations/executor.py"", line 63, in migrate
    self.apply_migration(migration, fake=fake)
  File ""/home/mitchell/myproject/local/lib/python2.7/site-packages/django/db/migrations/executor.py"", line 97, in apply_migration
    migration.apply(project_state, schema_editor)
  File ""/home/mitchell/myproject/local/lib/python2.7/site-packages/django/db/migrations/migration.py"", line 107, in apply
    operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
  File ""/home/mitchell/myproject/local/lib/python2.7/site-packages/django/db/migrations/operations/fields.py"", line 139, in database_forwards
    schema_editor.alter_field(from_model, from_field, to_field)
  File ""/home/mitchell/myproject/local/lib/python2.7/site-packages/django/db/backends/schema.py"", line 459, in alter_field
    raise ValueError(""Cannot alter field %s into %s - they do not properly define db_type (are you using PostGIS 1.5 or badly-written custom fields?)"" % (
ValueError: Cannot alter field main.Venue.coordinates into main.Venue.coordinates - they do not properly define db_type (are you using PostGIS 1.5 or badly-written custom fields?)
}}}

Django 1.7.1."	Bug	assigned	GIS	1.7	Normal				Accepted	1	0	0	0	0	0