Django ListView

Summary: in this tutorial, you’ll learn how to use the Django ListView to display a list of tasks for the Todo list application.

This tutorial begins where the Django Todo App tutorial left off.

Introduction to the class-based views

In the previous tutorials, you have learned how to build a blog application using function-based views.

The function-based views are simple but flexible. In the earlier versions, Django only supported function-based views. Later, Django added support for class-based views that allow you to define views using classes.

Class-based views are an alternative way to implement views. They do not replace the function-based views. However, they have some advantages in comparison with the function-based views:

• Organize code related to HTTP methods like GET and POST using separate methods, instead of conditional branching in the same function.
• Leverage multiple inheritances to create reusable view classes.

We’ll use the class-based views to build the Todo application.

You can download the final code for this Django ListView tutorial here.

Defining a class-based view

To display a list of objects, you define a class that inherits from the ListView class. For example, the following defines the TaskList class in the views.py of the todo application:

from django.shortcuts import render
from django.views.generic.list import ListView
from .models import Task

class TaskList(ListView):
    model = Task
    context_object_name = 'tasks'

# ...
   
Code language: Python (python)

The TaskList is a class based-view that inherits from the ListView class. In the TaskList class, we define the following attributes:

• model specifies the objects from which model you want to display. In this example, we use the Task model. Internally, Django will query all objects from the Task model (Task.objects.all()) and pass it to a template.
• context_object_name specifies the variable name of the model list in the template. By default, Django uses object_list. However, the name object_list is quite generic. Therefore, we override the context_object_name by setting its value to tasks.

By convention, the TaskList class will load the todo/task_list.html template. The template name follows this convention:

app/model_list.htmlCode language: Python (python)

If you want to set a different name, you can use the template_name attribute. In this tutorial, we’ll use the default template name, which is task_list.html.

Define a route

Change the urls.py of the todo application to the following:

from django.urls import path
from .views import home, TaskList

urlpatterns = [
    path('', home, name='home'),
    path('tasks/', TaskList.as_view(),name='tasks'),
]
Code language: Python (python)

How it works.

First, import the TaskList class from the views.py module.

from .views import home, TaskListCode language: Python (python)

Second, define tasks/ URL that displays the task list:

path('tasks/', TaskList.as_view(),name='tasks'),Code language: Python (python)

In this code, we map the URL tasks/ to the result of the as_view() method of the TaskList class.

Note that you can specify the attributes of the TaskList class in the as_view() method. For example, you can pass a template name to the as_view() method as follows:

path('tasks/', TaskList.as_view(template_name='mytodo.html'),name='tasks'),Code language: Python (python)

The as_view() method has arguments which are corresponding to the attributes of the TaskList class.

Creating a Django ListView template

Define the task_list.html in the templates/todo directory of the Todo app:

{%extends 'base.html'%}

{%block content%}

<div class="center">
	<h2>My Todo List</h2>
	{% if tasks %}
	<ul class="tasks">
		{% for task in tasks %}
			<li><a href="#" class="{% if task.completed%}completed{%endif%}">{{ task.title }}</a> 
				 <div  class="task-controls">
				 	<a href="#"><i class="bi bi-trash"></i> </a>
					<a href="#"><i class="bi bi-pencil-square"></i></a>
		         </div>
		    </li>
		{% endfor %}
	{% else %}
		<p>🎉 Yay, you have no pending tasks!</p>
	{% endif %}
	</ul>
</div>
{%endblock content%}Code language: HTML, XML (xml)

The task_list.html template extends the base.html template of the project. In the task_list.html template, we iterate over the tasks QuerySet and display each of them as an item on a list.

Also, we add the completed CSS class to the a tag if the task is completed. This CSS class will add a line-through to the item.

If the tasks QuerySet is empty, we display a message saying that there are no pending tasks.

Including ListView link in the base template

Modify the base.html template to include the My Tasks link in the navigation:

{%load static %}
<!DOCTYPE html>
<html lang="en">

    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <link rel="stylesheet" href="{% static 'css/style.css' %}" />
        <title>Todo List</title>
    </head>

    <body>
        <header class="header">
            <div class="container">
            	<a href="{%url 'home'%}" class="logo">Todo</a>
                <nav class="nav">
                	<a href="{%url 'home'%}"><i class="bi bi-house-fill"></i> Home</a>
                	<a href="{% url 'tasks' %}"><i class="bi bi-list-task"></i> My Tasks</a>
                </nav>
            </div>
        </header>
        <main>
            <div class="container">
             {%block content %}
             {%endblock content%}
            </div>
        </main>
        <footer class="footer">
            <div class="container">
               <p>© Copyright {% now "Y" %} by <a href="https://www.pythontutorial.net">Python Tutorial</a></p>
            </div>
        </footer>
    </body>

</html>
Code language: HTML, XML (xml)

If you open the URL:

http://128.0.0.1:8000/tasks/Code language: Python (python)

you’ll see the task list as follows:

You can download the final code for this Django ListView tutorial here.

Summary

• Create a class-based view that displays a list of objects by inheriting from the ListView class.