How to Show a Many-to-Many Field with "list_display" in Django Admin

In Django, the list_display attribute in the Django Admin interface allows developers to specify which fields to display in the list view of the admin panel. This feature is particularly useful for providing a quick overview of the model instances. However, displaying many-to-many fields in the list_display can be a bit tricky since these fields can contain multiple values. This article will guide you through the steps to create a Django project and show how to display a many-to-many field in the list_display attribute of the Django Admin.

How to Show a Many-to-Many Field with "list_display" in Django Admin?

Before we dive into the specifics of displaying many-to-many fields in the Django Admin, let's set up a basic Django project. We will create a simple application that includes models with many-to-many relationships

1. Create a Django Project

First, ensure you have Django installed. If not, you can install it using pip:

pip install django

Create a new Django project:

django-admin startproject myproject
cd myproject

2. Create a Django App

Within the project, create a new app. Let's call it library.

python manage.py startapp library

Add the new app to your project’s INSTALLED_APPS in myproject/settings.py:

INSTALLED_APPS = [
    ...
    'library',
    ...
]

3. Define Models

In the library/models.py file, define the models for your application. We'll create Book and Author models with a many-to-many relationship.

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100)

    def __str__(self):
        return self.name

class Book(models.Model):
    title = models.CharField(max_length=200)
    authors = models.ManyToManyField(Author)

    def __str__(self):
        return self.title

4. Apply Migrations

After defining the models, apply the migrations to create the corresponding tables in the database.

python manage.py makemigrations
python manage.py migrate

Displaying Many-to-Many Fields in Django Admin

To display many-to-many fields in the Django Admin list view, we need to define a custom method in the model admin class and use it in the list_display attribute.

1. Register Models in Admin

In library/admin.py, register the Book model with the Django Admin site and create a custom admin class.

In the BookAdmin class, the get_authors method fetches the list of authors associated with a book and returns their names as a comma-separated string. The get_authors.short_description attribute is used to set a readable column name in the admin interface.

from django.contrib import admin
from .models import Book, Author

class BookAdmin(admin.ModelAdmin):
    list_display = ('title', 'get_authors')

    def get_authors(self, obj):
        return ", ".join([author.name for author in obj.authors.all()])
    get_authors.short_description = 'Authors'

admin.site.register(Book, BookAdmin)
admin.site.register(Author)

2. Running the Development Server

Now, let's run the development server and see the changes in the admin panel.

python manage.py runserver

Go to the Django Admin site (usually at http://127.0.0.1:8000/admin/), log in, and navigate to the Book section. You should now see a list of books with their associated authors displayed in the list view.

Conclusion

Displaying many-to-many fields in the Django Admin interface using the list_display attribute involves defining a custom method in the model admin class. This method retrieves and formats the related data for display. This technique provides a clear and concise way to manage and view related objects directly from the admin interface, enhancing the usability and functionality of Django's built-in administrative tools. By following this guide, you can easily display many-to-many relationships in your Django projects, making it easier to manage complex data structures.