Login, Logout, and Built-in Auth Views

# mysite/urls.py — include built-in auth URLs
from django.urls import path, include

urlpatterns = [
    # Provides: login, logout, password_change, password_reset, etc.
    path('accounts/', include('django.contrib.auth.urls')),
]

# mysite/settings.py — auth redirect settings
LOGIN_URL           = '/accounts/login/'
LOGIN_REDIRECT_URL  = '/blog/'
LOGOUT_REDIRECT_URL = '/accounts/login/'

# templates/registration/login.html — override the default login template
# {% extends "base.html" %}
# {% block content %}
# <form method="post">
#   {% csrf_token %}
#   {{ form.as_p }}
#   <button type="submit">Log In</button>
# </form>
# {% endblock %}

# blog/views.py — protecting a view
from django.contrib.auth.decorators import login_required

@login_required
def dashboard(request):
    posts = request.user.posts.all()
    return render(request, 'blog/dashboard.html', {'posts': posts})

# Template usage
# {% if user.is_authenticated %}
#   <p>Welcome, {{ user.username }}!</p>
#   <a href="{% url 'logout' %}">Log out</a>
# {% else %}
#   <a href="{% url 'login' %}">Log in</a>
# {% endif %}