📘 Django – Guide 6: Authentication (Login & Logout)

This guide explains how to add user authentication (login + logout) to your Django project. You will build a simple login form, protect pages using the @login_required decorator, and enable logout functionality.

📌 Note: The repository includes a sample SQLite database (db.sqlite3) with preloaded tables and test data.

Available login credentials:

• User account: user / demo
• Admin account: admin / root

By the end of this guide, you will be able to:

• ✅ Create a users app for handling login + logout
• ✅ Add URL routes for /users/login/ and /users/logout/
• ✅ Implement login_view and logout_view
• ✅ Create a Bootstrap login page
• ✅ Add authentication links to the global footer
• ✅ Protect pages using @login_required
• ✅ Redirect users after login/logout
• ✅ Make everything work using your SQLite setup

---

📁 Project Structure

project_folder/
├── manage.py
│
├── core/
│   ├── settings.py
│   └── urls.py
│
├── apps/
│   ├── users/
│   │   ├── apps.py
│   │   ├── urls.py
│   │   ├── views.py
│   │   └── templates/users/login.html
│   │
│   ├── uom/
│   │   ├── views.py   ← protected with @login_required
│   │   └── ...
│   │
│   └── <other-apps>/
│
├── templates/
│   └── base.html       ← login/logout links in footer
│
└── db.sqlite3

---

⚙️ 1. Add Authentication Settings in core/settings.py

These settings control where to redirect after login and logout:

LOGIN_URL = '/users/login/'
LOGIN_REDIRECT_URL = '/'
LOGOUT_REDIRECT_URL = '/users/login/'

Also ensure your INSTALLED_APPS includes:

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'debug_toolbar',
    'apps.users',     # <-- our Authentication app
    'apps.uom',
    'apps.categories',
    'apps.doctype',
    'apps.items',
    'apps.compute',
]

---

🔗 2. Add User Routes in core/urls.py

urlpatterns = [
    path('', include('apps.uom.urls')),
    path('admin/', admin.site.urls),
    path('users/', include('apps.users.urls')),
    path('categories/', include('apps.categories.urls')),
    path('doctype/', include('apps.doctype.urls')),
    path('items/', include('apps.items.urls')),
    path('compute/', include('apps.compute.urls')),
]

---

🧩 3. Create the users App Configuration

apps/users/apps.py:

from django.apps import AppConfig

class AuthConfig(AppConfig):
    default_auto_field = 'django.db.models.BigAutoField'
    name = 'apps.users'

---

🌐 4. Create Authentication URLs

apps/users/urls.py:

from django.urls import path
from . import views

urlpatterns = [
    path('login/', views.login_view, name='login'),
    path('logout/', views.logout_view, name='logout'),
]

---

🧠 5. Create Authentication Views

apps/users/views.py:

from django.shortcuts import render, redirect
from django.contrib.auth import authenticate, login
from django.contrib import messages
from django.contrib.auth import logout

def login_view(request):
    if request.method == "POST":
        username = request.POST.get("username")
        password = request.POST.get("password")

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

        if user:
            login(request, user)
            return redirect('/')  # Home page
        else:
            messages.error(request, "Invalid username or password")

    return render(request, 'users/login.html')


def logout_view(request):
    logout(request)
    return redirect('login')

---

🎨 6. Create the Login Page Template

apps/users/templates/users/login.html:

{% extends 'base.html' %}

{% block title %}Login{% endblock %}

{% block content %}
<div class="card shadow-lg p-4 mb-3" style="max-width: 450px; margin: 0 auto;">

    <h4 class="mb-4 text-center">Login</h4>

    {% if messages %}
        {% for message in messages %}
            <div class="alert alert-danger py-2">{{ message }}</div>
        {% endfor %}
    {% endif %}

    <form method="POST">
        {% csrf_token %}

        <div class="mb-3">
            <label class="form-label">Username</label>
            <input type="text" name="username" class="form-control" required autofocus>
        </div>

        <div class="mb-3">
            <label class="form-label">Password</label>
            <input type="password" name="password" class="form-control" required>
        </div>

        <button type="submit" class="btn btn-primary w-100">Login</button>
    </form>

</div>
{% endblock %}

---

🦶 7. Add Login / Logout Links in the Footer

templates/base.html:

{% if user.is_authenticated %}
    <a class="ln" href="{% url 'logout' %}">「ろぐあうと」</a>
{% else %}
    <a class="ln" href="{% url 'login' %}">「ろぐいん」</a>
{% endif %}

Users instantly see login/logout options anywhere in the project.

---

🔐 8. Protect Pages Using @login_required

Example (apps/uom/views.py):

from django.contrib.auth.decorators import login_required

@login_required
def index(request):
    ...

Any user who isn’t logged in is automatically redirected to:

/users/login/?next=/requested/page/

---

🧪 9. Test the Full Authentication Flow

1️⃣ Visit:

http://localhost:8000/users/login/

2️⃣ Enter a valid Django admin user

(you can create one with python manage.py createsuperuser)

3️⃣ After login → Redirects to /

4️⃣ Logout from the footer

Everything should work exactly like Guide 5 with the same clarity and flow.

---

🎉 Done! Authentication is Fully Working

You now have:

• ✔ Login page with Bootstrap
• ✔ Logout functionality
• ✔ Redirects after login/logout
• ✔ Footer showing login/logout options
• ✔ Protected views using @login_required
• ✔ Smooth integration with your current project
• ✔ No migrations needed — purely Django built-in auth