#models.py in main/ app
class Mileage(models.Model):
    owner = models.ForeignKey(User)

#views.py in accounts/ app
def main(request):
print (request.user.is_authenticated())

title = "Login"
form = UserLoginForm(request.POST or None)
context = {
    "title": title,
    "form": form,
}

if form.is_valid():
    username = form.cleaned_data.get("username")
    password = form.cleaned_data.get("password")
    user = authenticate(username=username, password=password)
    login(request,user)
    print (request.user.is_authenticated())
    return redirect('home/')

context = {
    "title": title,
    "form": form,

}

return render(request, "main.html", context)

#forms.py in accounts/ app
User = get_user_model()

class UserLoginForm(forms.Form):
username = forms.CharField()
password = forms.CharField(widget=forms.PasswordInput)

def clean(self, *args, **kwargs):
    username = self.cleaned_data.get("username")
    password = self.cleaned_data.get("password")

    if username and password:
        user = authenticate(username = username, password = password)
        if not user:
            raise forms.ValidationError("This user does not exist")
        if not user.check_password(password):
            raise forms.ValidationError("Incorrect password")
        if not user.is_active:
            raise forms.ValidationError("This user is no longer active")
    return super(UserLoginForm,self).clean(*args, **kwargs)