from django.contrib.admin.helpers import ACTION_CHECKBOX_NAME

from django.contrib.admin.options import ModelAdmin, HORIZONTAL, VERTICAL

from django.contrib.admin.options import StackedInline, TabularInline

from django.contrib.admin.sites import AdminSite, site

from django.utils.importlib import import_module

# A flag to tell us if autodiscover is running.  autodiscover will set this to

# True while running, and False when it finishes.

LOADING = False

def autodiscover():

    """

    Auto-discover INSTALLED_APPS admin.py modules and fail silently when

    not present. This forces an import on them to register any admin bits they

    may want.

    """

    # Bail out if autodiscover didn't finish loading from a previous call so

    # that we avoid running autodiscover again when the URLconf is loaded by

    # the exception handler to resolve the handler500 view.  This prevents an

    # admin.py module with errors from re-registering models and raising a

    # spurious AlreadyRegistered exception (see #8245).

    global LOADING

    if LOADING:

        return

    LOADING = True

    import imp

    from django.conf import settings

    for app in settings.INSTALLED_APPS:

        # For each app, we need to look for an admin.py inside that app's

        # package. We can't use os.path here -- recall that modules may be

        # imported different ways (think zip files) -- so we need to get

        # the app's __path__ and look for admin.py on that path.

        # Step 1: find out the app's __path__ Import errors here will (and

        # should) bubble up, but a missing __path__ (which is legal, but weird)

        # fails silently -- apps that do weird things with __path__ might

        # need to roll their own admin registration.

        try:

            app_path = import_module(app).__path__

        except AttributeError:

            continue

        # Step 2: use imp.find_module to find the app's admin.py. For some

        # reason imp.find_module raises ImportError if the app can't be found

        # but doesn't actually try to import the module. So skip this app if

        # its admin.py doesn't exist

        try:

            imp.find_module('admin', app_path)

        except ImportError:

            continue

        # Step 3: import the app's admin file. If this has errors we want them

        # to bubble up.

        import_module("%s.admin" % app)

    # autodiscover was successful, reset loading flag.

    LOADING = False