makemigrations fails on model with geometry field when the geo database is not the default one

[Kaveh]

Create a django app with two databases defined like this:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'whatever'
        ...
    },
    'postgres': {
        'ENGINE': 'django.contrib.gis.db.backends.postgis',
        'NAME': 'whatever'
    }
}

and here is the database router:

POSTGRES_APPS = ['app1']


class PostgresRouter(object):
    def db_for_read(self, model, **hints):
        if model._meta.app_label in POSTGRES_APPS:
            return 'postgres'
        return None

    def db_for_write(self, model, **hints):
        if model._meta.app_label in POSTGRES_APPS:
            return 'postgres'
        return None

    def allow_relation(self, obj1, obj2, **hints):
        if {obj1._meta.app_label, obj2._meta.app_label}.issubset(set(POSTGRES_APPS)):
            return True
        return None

    def allow_migrate(self, db, app_label, model_name=None, **hints):
        if db == 'postgres':
            return app_label in POSTGRES_APPS
        else:
            return app_label not in POSTGRES_APPS

Create an app called app1 and add it to INSTALLED_APPS:

class Shapes(models.Model):
    shape = models.GeometryField()

Now if you run makemigrations, it throws the following error:
AttributeError: 'DatabaseOperations' object has no attribute 'geo_db_type'

Seems like the error is because Django is using the default connection, i.e. mysql, for handling the geomtry field in app1, though this app is supposed to be part of the gis enabled database, i.e. postgres.

[Simon Charette]

Hello Kaveh,

Did you reproduce against 1.11 as well? Would it be possible for you to provide the full traceback of the AttributeError?

[Kaveh]

Hi Simon, I just tried with Django 1.11 and everything works fine there. Unfortunately I'm stuck with Django 1.8.14 right now and upgrade is not an option for me.
Here's the full traceback:

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 354, in execute_from_command_line
    utility.execute()
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 346, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/core/management/base.py", line 394, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/core/management/base.py", line 444, in execute
    self.check()
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/core/management/base.py", line 482, in check
    include_deployment_checks=include_deployment_checks,
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/core/checks/registry.py", line 72, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/core/checks/model_checks.py", line 28, in check_all_models
    errors.extend(model.check(**kwargs))
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/db/models/base.py", line 1205, in check
    errors.extend(cls._check_fields(**kwargs))
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/db/models/base.py", line 1282, in _check_fields
    errors.extend(field.check(**kwargs))
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 207, in check
    errors.extend(self._check_backend_specific_checks(**kwargs))
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 306, in _check_backend_specific_checks
    return connection.validation.check_field(self, **kwargs)
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/db/backends/mysql/validation.py", line 18, in check_field
    field_type = field.db_type(connection)
  File "/home/user/sandbox/venv/local/lib/python2.7/site-packages/django/contrib/gis/db/models/fields.py", line 247, in db_type
    return connection.ops.geo_db_type(self)
AttributeError: 'DatabaseOperations' object has no attribute 'geo_db_type'

Replying to Simon Charette:

Hello Kaveh,

Did you reproduce against 1.11 as well? Would it be possible for you to provide the full traceback of the AttributeError?

[Tim Graham]

Per our ​supported versions policy, 1.8 is only receiving security and data loss fixes so we can close this. Thanks for checking.