from django.contrib.auth import authenticate
from django.contrib.auth import login as user_login
def my_login(request):
    """
    登錄視圖
    :param request:
    :return:
    """
    if request.method == "POST":
        login_form = users_form.UserForm(request.POST)
        if login_form.is_valid():
            username = login_form.cleaned_data['username']
            password = login_form.cleaned_data['password']
            myuser = authenticate(username=username, password=password)
            if myuser is not None:
                user_login(request, myuser)

@sensitive_variables("credentials")
def authenticate(request=None, **credentials):
    """
    If the given credentials are valid, return a User object.
    """
    for backend, backend_path in _get_backends(return_tuples=True):
        backend_signature = inspect.signature(backend.authenticate)
        try:
            backend_signature.bind(request, **credentials)
        except TypeError:
            # This backend doesn't accept these credentials as arguments. Try
            # the next one.
            continue
        try:
            user = backend.authenticate(request, **credentials)
        except PermissionDenied:
            # This backend says to stop in our tracks - this user should not be
            # allowed in at all.
            break
        if user is None:
            continue
        # Annotate the user object with the path of the backend.
        user.backend = backend_path
        return user

def _get_backends(return_tuples=False):
    backends = []
    for backend_path in settings.AUTHENTICATION_BACKENDS:
        backend = load_backend(backend_path)
        backends.append((backend, backend_path) if return_tuples else backend)
    if not backends:
        raise ImproperlyConfigured(
            "No authentication backends have been defined. Does "
            "AUTHENTICATION_BACKENDS contain anything?"
        )
    return backends

AUTHENTICATION_BACKENDS = [
    'django.contrib.auth.backends.ModelBackend',
    'backends.user_backend.UserBackend'
]

from django.contrib.auth.backends import BaseBackend
from users.models import MyUser
class UserBackend(BaseBackend):
    def authenticate(self, request, username=None, password=None, **kwargs):
        try:
            myuser = MyUser.objects.get(name=username)
            if myuser.check_password(password):
                return myuser
        except MyUser.DoesNotExist as e:
            print("user no exist", e)
            return None
    def get_user(self, user_id):
        try:
            return MyUser.objects.get(pk=user_id)
        except MyUser.DoesNotExist:
            return None