python/lib/django-0.96/django/contrib/auth/__init__.py

   1 from django.core.exceptions import ImproperlyConfigured
   2
   3 SESSION_KEY = '_auth_user_id'
   4 BACKEND_SESSION_KEY = '_auth_user_backend'
   5 LOGIN_URL = '/accounts/login/'
   6 REDIRECT_FIELD_NAME = 'next'
   7
   8 def load_backend(path):
   9     i = path.rfind('.')
  10     module, attr = path[:i], path[i+1:]
  11     try:
  12         mod = __import__(module, {}, {}, [attr])
  13     except ImportError, e:
  14         raise ImproperlyConfigured, 'Error importing authentication backend %s: "%s"' % (module, e)
  15     try:
  16         cls = getattr(mod, attr)
  17     except AttributeError:
  18         raise ImproperlyConfigured, 'Module "%s" does not define a "%s" authentication backend' % (module, attr)
  19     return cls()
  20
  21 def get_backends():
  22     from django.conf import settings
  23     backends = []
  24     for backend_path in settings.AUTHENTICATION_BACKENDS:
  25         backends.append(load_backend(backend_path))
  26     return backends
  27
  28 def authenticate(**credentials):
  29     """
  30     If the given credentials are valid, return a User object.
  31     """
  32     for backend in get_backends():
  33         try:
  34             user = backend.authenticate(**credentials)
  35         except TypeError:
  36             # This backend doesn't accept these credentials as arguments. Try the next one.
  37             continue
  38         if user is None:
  39             continue
  40         # Annotate the user object with the path of the backend.
  41         user.backend = "%s.%s" % (backend.__module__, backend.__class__.__name__)
  42         return user
  43
  44 def login(request, user):
  45     """
  46     Persist a user id and a backend in the request. This way a user doesn't
  47     have to reauthenticate on every request.
  48     """
  49     if user is None:
  50         user = request.user
  51     # TODO: It would be nice to support different login methods, like signed cookies.
  52     request.session[SESSION_KEY] = user.id
  53     request.session[BACKEND_SESSION_KEY] = user.backend
  54
  55 def logout(request):
  56     """
  57     Remove the authenticated user's ID from the request.
  58     """
  59     try:
  60         del request.session[SESSION_KEY]
  61     except KeyError:
  62         pass
  63     try:
  64         del request.session[BACKEND_SESSION_KEY]
  65     except KeyError:
  66         pass
  67
  68 def get_user(request):
  69     from django.contrib.auth.models import AnonymousUser
  70     try:
  71         user_id = request.session[SESSION_KEY]
  72         backend_path = request.session[BACKEND_SESSION_KEY]
  73         backend = load_backend(backend_path)
  74         user = backend.get_user(user_id) or AnonymousUser()
  75     except KeyError:
  76         user = AnonymousUser()
  77     return user