URL Dispatcher for CRUD Views

As we explained in Chapter 2, The URL dispatcher is one of the key concepts in the Django architecture. The URL dispatcher maps HTTP requests to the view functions or classes specified in the URL patterns written in the urls.py file.

In the case on the previous page, as there are five basic CRUD views, you need to prepare five URL patterns. Usually, application-specific URL patterns are written in the urls.py file in each app directory.

1. Two urls.py files

There are two urls.py files you need to handle:

• Project urls.py: This file is created by the startproject command
• App urls.py: A new urls.py file under the app directory. This file is not created by the startproject and startapp commands. You need to create it yourself.

2. Create and Edit App urls.py

As the app urls.py file is not automatically created, you need to create it first. Then, edit the file with the guidance below.

Import views

First, you need to import the necessary modules. You need to import all views from views.py.

Add the five URL patterns

You need to add one URL pattern for each view. There are three arguments when you set URL patterns.

1. URL

In this part, you can set a URL you want to use. To avoid confusion, use a slug related to the view. Usually, the kebab-case is used for this part. You can set a variable in a part of the URL using path converter <>, which will be explained later.

2. View name

In this part, you can specify which view you want to link to the URL. For class-based views, usually, PascalCase is used. You need to add .as_view() after the view name for class-based views. You don't need to add .as_view() when you use function-based views.

3. URL name

In Chapter 2, we only covered the first two arguments but not the name argument. The name argument is useful when you handle the reverse URL resolution. For example, by setting this, you can call the URL in views.py.

Path converter – <init:pk>

Using a path converter, you can set a variable in the URL. The variable is defined using angle brackets <>. The most frequently used one is <int:pk>. The int part is a data type. int means zero or any positive integer. The pk part is a variable. pk means primary key, which is set in the auto-generated id field by default. <int:pk> is just an example. You can set other types of path converters using the <data type:name> format. The data type examples are:

• str - Matches any non-empty string
• slug - Matches any slug string consisting of ASCII letters or numbers, plus the hyphen and underscore characters

3. Edit the project urls.py file

Creating and editing the urls.py file under the app directory is not enough to complete the URL dispatcher. You need to link the newly created urls.py file with the project urls.py file by adding the include function, as in the example below.

cd employee_learning
touch urls.py

from django.urls import path
from .views import CourseList, CourseDetail, CourseCreate, CourseUpdate, CourseDelete

from django.urls import path
from .views import CourseList, CourseDetail, CourseCreate, CourseUpdate, CourseDelete

urlpatterns = [
    path('course-list/', CourseList.as_view(), name='course_list'),
    path('course-create/', CourseCreate.as_view(), name='course_create'),
]

 : 
urlpatterns = [
    path('course-list/', CourseList.as_view(), name='course_list'),
    path('course-detail/<int:pk>/', CourseDetail.as_view(), name='course_detail'),
    path('course-create/', CourseCreate.as_view(), name='course_create'),
    path('course-update/<int:pk>/', CourseUpdate.as_view(), name='course_update'),
    path('course-delete/<int:pk>/', CourseDelete.as_view(), name='course_delete'),
]

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('test-app/', include('test_app.urls')),
    path('employee-learning/', include('employee_learning.urls')),
]

Django documentation reference: URL dispacher