My newly registered user can login to my django web app

Question

I am new to the community. I usually am able to just find my answer, but I have been searching and searching, and can't seem to find anything similar to what I've got going on. I have a ModelForm set up to register new users. I got it to work, and send information over to the sqlite database. However, when I try to log the newly registered user in it says:

"Please enter a correct username and password. Note that both fields may be case-sensitive."

login.html:

{% extends 'app/register.html' %}

{% block content %}
<h2>Login</h2>

<form method="post">
    {% csrf_token %}
    {{ form.as_p }}
    <input type="submit" value="Login">
</form>

<a href="{% url 'index' %}">Back to Homepage</a>
<br>
<a href="{% url 'password_reset' %}">Reset password</a>
<br>
<a href="{% url 'register' %}">Register</a>
{% endblock %}

views.py

from django.contrib.auth import authenticate, login
from django.contrib.auth.models import User
from django.contrib.auth.forms import UserCreationForm
from django.contrib.auth.decorators import login_required
from datetime import datetime
from django.http import HttpRequest
from django.shortcuts import render, redirect
from django.urls import reverse
from . import forms
from django.contrib import auth

def index(request):
    """Renders the home page."""
    assert isinstance(request, HttpRequest)
    return render(
        request,
        'app/index.html',
        {
            'title':'Home Page',
            'year':datetime.now().year,
        }
    )
    
def register(request):
    
    if request.method == "GET":
        form = forms.Registration(request.GET)
        return render(
        request, "app/register.html",
        {"form": form}
        )
    elif request.method == "POST":
        form = forms.Registration(request.POST)
        if form.is_valid():
            user = form.save()
            login(request, user)
            return redirect(reverse("index"))

models.py

from django.contrib.auth.models import User
from django.db import models

# Create your models here.
class Patient(models.Model):
    first_name = models.CharField(max_length=100)
    last_name = models.CharField(max_length=100)
    #birthdate = models.DateField(auto_now=False, null=True, blank=True)
    gender = models.CharField(max_length=100, blank=True)
    allergies = models.TextField(blank=True)
    email = models.CharField(max_length=200)
    username = models.CharField(max_length=100)
    password = models.CharField(max_length=100)
    last_login = models.CharField(max_length=100)

and forms.py:

from django import forms
from . import models
from django.contrib.auth.forms import AuthenticationForm
from django.utils.translation import ugettext_lazy as _
from django.contrib.auth.models import User

class Registration(forms.ModelForm):
    class Meta:
        model = models.Patient
        fields = ('first_name','last_name', 'gender', 'email', 'username', 'password', 'allergies',)

any help would be greatly appreciated. Please forgive me if I've left something out, just let me know. Thank you!

Answer 1

So after a lot of trial and error and fiddling, I ultimately fixed it this way, thanks to Abdul Aziz Barkat's suggestion above.

I changed Patient(models.Model) to Patient(AbstractUser)

And then I also had to change the Registration(forms.ModelForm) to Registration(UserCreationForm). All of the users are authenticating just fine now, thank you!