Authenticate user using email and password

Question

I have a form that only allow users to login via username . I decided to only allow user to login via email instead of username.

First, this is not a duplication of any

Answer 1

Looks like you are testing against 2 different fields. You look for the user against email

if User.objects.filter(email=user).exists():

but then validate against username

user = authenticate(username=user, password=password)

If you are using the email address the auth line should be

user = authenticate(email=user, password=password)

Answer 2

You can also write a custom backend:

# yourapp.backends.py    
from django.contrib.auth.models import User


class EmailOrUsernameModelBackend(object):
    """ Authenticate user by username or email """
    def authenticate(self, username=None, password=None):
        if '@' in username:
            kwargs = {'email': username}
        else:
            kwargs = {'username': username}
        try:

            user = User.objects.get(**kwargs)
            if user.check_password(password):
                return user
            else:
                return None
        except User.DoesNotExist:
            return None

    def get_user(self, user_id=None):
        try:
            return User.objects.get(pk=user_id)
        except User.DoesNotExist:
            return None

Now add your backend to settings.py:

AUTHENTICATION_BACKENDS = (
    'yourapp.backends.EmailOrUsernameModelBackend',
    'django.contrib.auth.backends.ModelBackend',
)

Answer 3

As dougis pointed out you are trying to authenticate the user using email, But authenticate function authenticates user based on username and password. So here is the trick to authenticate the user using email (complete working form):

from django.db.models import Q
from django.core.exceptions import ObjectDoesNotExist
from django.contrib.auth.models import User
from django import forms
from django.contrib.auth import authenticate

class LoginForm(forms.Form):
    email = forms.CharField()
    password = forms.CharField(
        widget=forms.PasswordInput(render_value=False)
        )

    def clean(self):
        user = self.authenticate_via_email()
        if not user:
            raise forms.ValidationError("Sorry, that login was invalid. Please try again.")
        else:
            self.user = user
        return self.cleaned_data

    def authenticate_user(self):
        return authenticate(
            username=self.user.username,
            password=self.cleaned_data['password'])

    def authenticate_via_email(self):
        """
            Authenticate user using email.
            Returns user object if authenticated else None
        """
        email = self.cleaned_data['email']
        if email:
            try:
                user = User.objects.get(email__iexact=email)
                if user.check_password(self.cleaned_data['password']):
                    return user
            except ObjectDoesNotExist:
                pass
        return None

views.py

def LoginRequest(request):
    form = LoginForm(request.POST or None)    
    if request.method == 'POST' and form.is_valid():
        user = form.authenticate_user()
        login(request, user)
        return HttpResponseRedirect(reverse('Hello'))

    return render(request, 'login.html',{'form': form})