Bài 04: URLs và Routing

URL Routing Trong Django

URL Routing Là Gì?

URL Routing là quá trình map URL patterns đến view functions/classes. Khi user truy cập URL, Django tìm pattern phù hợp và gọi view tương ứng.

Flow:

User Request → URL Pattern → View → Response Example:1. User: https://example.com/blog/2023/django-tutorial/2. Django: Tìm pattern phù hợp3. Pattern: blog/<int:year>/<slug:slug>/4. View: post_detail(request, year, slug)5. Response: Render template với post data

URLconf (URL Configuration)

Django dùng URLconf để define URL patterns. URLconf là Python module chứa urlpatterns list.

Cấu trúc URLconf:

# mysite/urls.py (Project-level URLconf)from django.contrib import adminfrom django.urls import path, include urlpatterns = [    path('admin/', admin.site.urls),           # Admin site    path('blog/', include('blog.urls')),       # Include blog URLs    path('shop/', include('shop.urls')),       # Include shop URLs    path('', include('pages.urls')),           # Include pages URLs] # blog/urls.py (App-level URLconf)from django.urls import pathfrom . import views app_name = 'blog'  # Namespace urlpatterns = [    path('', views.post_list, name='post_list'),    path('<slug:slug>/', views.post_detail, name='post_detail'),    path('category/<slug:category>/', views.category, name='category'),]

URL Resolution Process

# Step-by-step process: # 1. User visits: http://example.com/blog/django-tutorial/ # 2. Django loads ROOT_URLCONF# settings.pyROOT_URLCONF = 'mysite.urls' # 3. Django checks mysite/urls.pyurlpatterns = [    path('blog/', include('blog.urls')),  # ← Match!] # 4. Django removes 'blog/' và checks blog/urls.py# Remaining: 'django-tutorial/'urlpatterns = [    path('<slug:slug>/', views.post_detail),  # ← Match!] # 5. Django calls viewviews.post_detail(request, slug='django-tutorial') # 6. View returns response

URL Patterns với path()

Basic path() Syntax

from django.urls import pathfrom . import views urlpatterns = [    # path(route, view, kwargs=None, name=None)    path('about/', views.about, name='about'),]

Parameters:

route: URL pattern string
view: View function hoặc class
kwargs: Extra arguments (optional)
name: URL name để reverse (optional)

Simple URL Patterns

# blog/urls.pyfrom django.urls import pathfrom . import views urlpatterns = [    # Homepage    path('', views.home, name='home'),        # Static URLs    path('about/', views.about, name='about'),    path('contact/', views.contact, name='contact'),    path('privacy/', views.privacy, name='privacy'),        # Blog URLs    path('posts/', views.post_list, name='post_list'),    path('posts/new/', views.post_create, name='post_create'),        # Nested URLs    path('archive/', views.archive, name='archive'),    path('archive/2023/', views.archive_2023, name='archive_2023'),] # blog/views.pyfrom django.shortcuts import render def home(request):    return render(request, 'blog/home.html') def about(request):    return render(request, 'blog/about.html') def post_list(request):    posts = Post.objects.all()    return render(request, 'blog/post_list.html', {'posts': posts})

URL Path Converters

Django cung cấp path converters để capture URL parameters:

Built-in Converters:

# blog/urls.pyfrom django.urls import pathfrom . import views urlpatterns = [    # 1. str - Matches any non-empty string (excluding '/')    # Default converter    path('posts/<str:slug>/', views.post_detail),    # Example: /posts/django-tutorial/ → slug='django-tutorial'        # 2. int - Matches zero or any positive integer    path('posts/<int:id>/', views.post_by_id),    # Example: /posts/123/ → id=123        # 3. slug - Matches slug string (letters, numbers, hyphens, underscores)    path('posts/<slug:slug>/', views.post_detail),    # Example: /posts/my-first-post/ → slug='my-first-post'        # 4. uuid - Matches UUID    path('posts/<uuid:id>/', views.post_by_uuid),    # Example: /posts/550e8400-e29b-41d4-a716-446655440000/        # 5. path - Matches any non-empty string (including '/')    path('files/<path:filepath>/', views.file_view),    # Example: /files/docs/2023/report.pdf → filepath='docs/2023/report.pdf']

Real Examples:

# blog/urls.pyfrom django.urls import pathfrom . import views app_name = 'blog' urlpatterns = [    # Post detail by slug    path('post/<slug:slug>/', views.post_detail, name='post_detail'),    # /blog/post/django-tutorial/        # Post detail by ID    path('post/<int:pk>/', views.post_detail_by_id, name='post_detail_by_id'),    # /blog/post/123/        # Archive by year    path('archive/<int:year>/', views.archive_year, name='archive_year'),    # /blog/archive/2023/        # Archive by year and month    path('archive/<int:year>/<int:month>/',          views.archive_month, name='archive_month'),    # /blog/archive/2023/10/        # Category posts    path('category/<slug:category_slug>/',          views.category_posts, name='category_posts'),    # /blog/category/python/        # Author posts    path('author/<str:username>/',          views.author_posts, name='author_posts'),    # /blog/author/john_doe/] # blog/views.pydef post_detail(request, slug):    post = get_object_or_404(Post, slug=slug)    return render(request, 'blog/post_detail.html', {'post': post}) def archive_year(request, year):    posts = Post.objects.filter(created__year=year)    return render(request, 'blog/archive.html', {'posts': posts, 'year': year}) def archive_month(request, year, month):    posts = Post.objects.filter(created__year=year, created__month=month)    context = {'posts': posts, 'year': year, 'month': month}    return render(request, 'blog/archive.html', context) def category_posts(request, category_slug):    category = get_object_or_404(Category, slug=category_slug)    posts = category.posts.all()    return render(request, 'blog/category.html', {'posts': posts, 'category': category})

Multiple Parameters

# blog/urls.pyurlpatterns = [    # Multiple parameters    path('posts/<int:year>/<int:month>/<slug:slug>/',         views.post_detail_with_date,         name='post_detail_with_date'),    # /blog/posts/2023/10/django-tutorial/        path('category/<slug:category>/tag/<slug:tag>/',         views.posts_by_category_and_tag,         name='posts_by_category_and_tag'),    # /blog/category/python/tag/beginners/] # blog/views.pydef post_detail_with_date(request, year, month, slug):    post = get_object_or_404(        Post,         created__year=year,        created__month=month,        slug=slug    )    context = {        'post': post,        'year': year,        'month': month,    }    return render(request, 'blog/post_detail.html', context) def posts_by_category_and_tag(request, category, tag):    posts = Post.objects.filter(        category__slug=category,        tags__slug=tag    )    context = {        'posts': posts,        'category': category,        'tag': tag,    }    return render(request, 'blog/post_list.html', context)

Advanced URL Patterns

re_path() với Regular Expressions

Khi path() không đủ, dùng re_path() với regex:

from django.urls import path, re_pathfrom . import views urlpatterns = [    # Named groups với regex    re_path(r'^articles/(?P<year>[0-9]{4})/$',             views.archive_year),    # /articles/2023/        re_path(r'^articles/(?P<year>[0-9]{4})/(?P<month>[0-9]{2})/$',            views.archive_month),    # /articles/2023/10/        # Optional trailing slash    re_path(r'^posts/(?P<slug>[-\w]+)/?$',            views.post_detail),    # /posts/django-tutorial or /posts/django-tutorial/        # Pattern with constraints    re_path(r'^user/(?P<username>[a-zA-Z0-9_]{3,20})/$',            views.user_profile),    # Username: 3-20 characters] # Regex syntax:# ^        - Start of string# $        - End of string# [0-9]    - Any digit# {4}      - Exactly 4 times# [-\w]    - Hyphen or word character# +        - One or more# ?        - Zero or one (optional)# (?P<name>...) - Named group

When to use re_path():

# ✅ Use re_path() when:# - Need complex patterns# - Need regex constraints# - Legacy URLs compatibility # ❌ Prefer path() when possible:# - Simpler# - More readable# - Faster

include() để Modularize URLs

# mysite/urls.py (Project-level)from django.contrib import adminfrom django.urls import path, include urlpatterns = [    path('admin/', admin.site.urls),        # Include app URLs    path('blog/', include('blog.urls')),    path('shop/', include('shop.urls')),    path('api/', include('api.urls')),        # Include with namespace    path('accounts/', include('django.contrib.auth.urls')),        # Empty path for homepage    path('', include('pages.urls')),] # blog/urls.py (App-level)from django.urls import path, includefrom . import views app_name = 'blog'  # Namespace # Blog URLsblog_patterns = [    path('', views.post_list, name='post_list'),    path('<slug:slug>/', views.post_detail, name='post_detail'),] # Comment URLs (nested)comment_patterns = [    path('add/', views.add_comment, name='add_comment'),    path('<int:pk>/edit/', views.edit_comment, name='edit_comment'),    path('<int:pk>/delete/', views.delete_comment, name='delete_comment'),] urlpatterns = [    path('posts/', include(blog_patterns)),    path('comments/', include(comment_patterns)),] # Final URLs:# /blog/posts/# /blog/posts/django-tutorial/# /blog/comments/add/# /blog/comments/123/edit/

URL Namespacing

# blog/urls.pyapp_name = 'blog'  # Namespace urlpatterns = [    path('', views.post_list, name='post_list'),    path('<slug:slug>/', views.post_detail, name='post_detail'),] # shop/urls.pyapp_name = 'shop'  # Namespace urlpatterns = [    path('', views.product_list, name='product_list'),    path('<slug:slug>/', views.product_detail, name='product_detail'),] # Usage in templates:{% url 'blog:post_list' %}           {# /blog/ #}{% url 'blog:post_detail' slug='django' %}  {# /blog/django/ #} {% url 'shop:product_list' %}        {# /shop/ #}{% url 'shop:product_detail' slug='laptop' %}  {# /shop/laptop/ #} # Usage in views:from django.urls import reverse # Without namespace (may conflict!)url = reverse('post_list')  # Which app??? # With namespace (clear!)url = reverse('blog:post_list')     # /blog/url = reverse('shop:product_list')  # /shop/

Passing Extra Options

# blog/urls.pyfrom django.urls import pathfrom . import views urlpatterns = [    # Pass extra kwargs to view    path('archive/',         views.archive,         {'format': 'html'},         name='archive'),        path('archive/json/',         views.archive,         {'format': 'json'},         name='archive_json'),        # Multiple extra kwargs    path('feed/',         views.feed,         {'format': 'rss', 'items': 20},         name='feed'),] # blog/views.pydef archive(request, format='html'):    posts = Post.objects.all()        if format == 'json':        from django.http import JsonResponse        data = list(posts.values('title', 'slug', 'created'))        return JsonResponse({'posts': data})        return render(request, 'blog/archive.html', {'posts': posts}) def feed(request, format='rss', items=10):    posts = Post.objects.all()[:items]    # Generate feed based on format    pass

URL Naming và Reversing

Why Name URLs?

# ❌ BAD - Hard-coded URLs<a href="/blog/posts/">Posts</a><a href="/blog/posts/django-tutorial/">Django Tutorial</a> # Problem: If URL changes, must update everywhere! # ✅ GOOD - Named URLs<a href="{% url 'blog:post_list' %}">Posts</a><a href="{% url 'blog:post_detail' slug='django-tutorial' %}">Django Tutorial</a> # Benefits:# - Change URL in one place (urls.py)# - Automatic updates everywhere# - Less errors

Naming URLs

# blog/urls.pyfrom django.urls import pathfrom . import views app_name = 'blog' urlpatterns = [    path('', views.post_list, name='post_list'),    path('new/', views.post_create, name='post_create'),    path('<slug:slug>/', views.post_detail, name='post_detail'),    path('<slug:slug>/edit/', views.post_edit, name='post_edit'),    path('<slug:slug>/delete/', views.post_delete, name='post_delete'),        # Naming convention:    # <model>_<action>    # post_list, post_detail, post_create, post_edit, post_delete]

Reversing URLs in Templates

{# blog/templates/blog/post_list.html #} {# Simple URL #}<a href="{% url 'blog:post_list' %}">All Posts</a> {# URL with slug parameter #}{% for post in posts %}    <a href="{% url 'blog:post_detail' slug=post.slug %}">        {{ post.title }}    </a>{% endfor %} {# URL with multiple parameters #}<a href="{% url 'blog:archive_month' year=2023 month=10 %}">    October 2023</a> {# URL with query string (manual) #}<a href="{% url 'blog:post_list' %}?page=2&sort=date">    Page 2</a>

Reversing URLs in Views

# blog/views.pyfrom django.shortcuts import redirectfrom django.urls import reversefrom django.http import HttpResponseRedirect def post_create(request):    if request.method == 'POST':        # Create post logic        post = Post.objects.create(...)                # Method 1: redirect() với URL name        return redirect('blog:post_detail', slug=post.slug)                # Method 2: reverse() then redirect        url = reverse('blog:post_detail', kwargs={'slug': post.slug})        return redirect(url)                # Method 3: HttpResponseRedirect        url = reverse('blog:post_detail', args=[post.slug])        return HttpResponseRedirect(url)        return render(request, 'blog/post_form.html') # More examples:def some_view(request):    # Simple URL    url = reverse('blog:post_list')    # Result: '/blog/'        # URL with parameters (kwargs)    url = reverse('blog:post_detail', kwargs={'slug': 'django-tutorial'})    # Result: '/blog/django-tutorial/'        # URL with parameters (args)    url = reverse('blog:archive_month', args=[2023, 10])    # Result: '/blog/archive/2023/10/'        # With namespace    url = reverse('blog:post_list')  # app_name:name        return redirect(url)

get_absolute_url() Pattern

# blog/models.pyfrom django.db import modelsfrom django.urls import reverse class Post(models.Model):    title = models.CharField(max_length=200)    slug = models.SlugField(unique=True)    content = models.TextField()        def get_absolute_url(self):        """Return canonical URL for post."""        return reverse('blog:post_detail', kwargs={'slug': self.slug})        def __str__(self):        return self.title # Usage in templates:# <a href="{{ post.get_absolute_url }}">{{ post.title }}</a> # Usage in views:def post_create(request):    if request.method == 'POST':        post = Post.objects.create(...)        return redirect(post.get_absolute_url())  # ← Clean!    return render(request, 'blog/post_form.html')

Bài Tập

Bài 1: Basic URL Routing

Task: Tạo blog app với các URLs:

# Requirements:# /blog/                    → List all posts# /blog/new/                → Create new post# /blog/<slug>/             → Post detail# /blog/<slug>/edit/        → Edit post# /blog/<slug>/delete/      → Delete post # Create files:# blog/urls.py# blog/views.py # Implement all views (can be simple for now)

Deliverables:

urls.py với 5 URL patterns
views.py với 5 view functions
Test tất cả URLs

Bài 2: URL Parameters

Task: Tạo archive system:

# URLs:# /blog/archive/                           → All years# /blog/archive/<year>/                    → Posts in year# /blog/archive/<year>/<month>/            → Posts in year/month# /blog/archive/<year>/<month>/<day>/      → Posts on date # blog/urls.pyurlpatterns = [    path('archive/', views.archive_index, name='archive_index'),    path('archive/<int:year>/', views.archive_year, name='archive_year'),    # ... complete the rest]

Bài 3: URL Namespacing

Task: Tạo 2 apps với similar URLs:

# blog/urls.pyapp_name = 'blog'urlpatterns = [    path('', views.post_list, name='list'),    path('<slug:slug>/', views.post_detail, name='detail'),] # shop/urls.pyapp_name = 'shop'urlpatterns = [    path('', views.product_list, name='list'),    path('<slug:slug>/', views.product_detail, name='detail'),] # Test namespacing:{% url 'blog:list' %}{% url 'shop:list' %}

Bài 4: URL Reversing

Task: Implement complete CRUD với URL reversing:

# blog/models.pyclass Post(models.Model):    # ... fields        def get_absolute_url(self):        return reverse('blog:detail', kwargs={'slug': self.slug}) # blog/views.pydef create_post(request):    # After creating post:    return redirect(post.get_absolute_url()) def edit_post(request, slug):    # After editing:    return redirect('blog:detail', slug=slug)

Tài Liệu Tham Khảo

Previous: Bài 03.2: Reusable Apps | Next: Bài 05: Views

#routing

URLs và Routing