ViewSets and routers in Django - Mini Project: Build & Apply

Building a Simple API with Django ViewSets and Routers

📖 Scenario: You are creating a small web API for a bookstore. The API will allow users to see a list of books and details about each book.

🎯 Goal: Build a Django API using ViewSets and routers to manage book data easily.

📋 What You'll Learn

Create a Django model for books with fields: title and author

Create a serializer for the Book model

Create a ViewSet for the Book model

Use a router to automatically generate URL routes for the Book API

💡 Why This Matters

🌍 Real World

APIs built with Django ViewSets and routers are common in web applications to provide easy and consistent access to data.

💼 Career

Understanding ViewSets and routers is essential for backend developers working with Django REST Framework to build scalable and maintainable APIs.

1

Create the Book model

Create a Django model called Book in models.py with two fields: title as a CharField with max length 100, and author as a CharField with max length 100.

Django

# Your code here

Hint

Remember to import models from django.db before defining the model.

2

Create the Book serializer

Create a serializer class called BookSerializer in serializers.py that uses serializers.ModelSerializer and includes all fields from the Book model.

Django

from django.db import models

class Book(models.Model):
    title = models.CharField(max_length=100)
    author = models.CharField(max_length=100)

# Your code here

Hint

Import serializers from rest_framework and create a Meta class inside your serializer.

3

Create the Book ViewSet

Create a ViewSet class called BookViewSet in views.py that inherits from viewsets.ModelViewSet. Set its queryset to all Book objects and its serializer_class to BookSerializer.

Django

from django.db import models

class Book(models.Model):
    title = models.CharField(max_length=100)
    author = models.CharField(max_length=100)

from rest_framework import serializers

class BookSerializer(serializers.ModelSerializer):
    class Meta:
        model = Book
        fields = '__all__'

# Your code here

Hint

Import viewsets from rest_framework and create the ViewSet class with the correct attributes.

4

Register the ViewSet with a router

In urls.py, import DefaultRouter from rest_framework.routers and BookViewSet from views. Create a router instance, register the BookViewSet with the prefix 'books', and set urlpatterns to the router's URLs.

Django

from django.db import models

class Book(models.Model):
    title = models.CharField(max_length=100)
    author = models.CharField(max_length=100)

from rest_framework import serializers

class BookSerializer(serializers.ModelSerializer):
    class Meta:
        model = Book
        fields = '__all__'

from rest_framework import viewsets

class BookViewSet(viewsets.ModelViewSet):
    queryset = Book.objects.all()
    serializer_class = BookSerializer

# Your code here

Hint

Import the router and the ViewSet, then register the ViewSet with the router and assign urlpatterns to router.urls.

Practice

1. What is the main purpose of using ViewSets in Django REST Framework?

easy

A. To group common web actions like list, create, update, and delete in one class

B. To define database models for the API

C. To write custom HTML templates for views

D. To handle user authentication manually

Solution

1. Step 1: Understand what ViewSets do

   ViewSets group common actions such as list, create, update, and delete into one class to simplify API views.

2. Step 2: Compare with other options

   Options B, C, and D describe unrelated tasks: models, templates, and authentication, which are not the main purpose of ViewSets.

3. Final Answer:

   To group common web actions like list, create, update, and delete in one class -> Option A

4. Quick Check:

   ViewSets group actions = A [OK]

Hint: ViewSets bundle common API actions together [OK]

Common Mistakes:

• Confusing ViewSets with models
• Thinking ViewSets handle templates
• Assuming ViewSets manage authentication

2. Which of the following is the correct way to register a ViewSet with a router in Django REST Framework?

easy

A. router.attach('items', ItemViewSet)

B. router.add('items', ItemViewSet)

C. router.register('items', ItemViewSet)

D. router.include('items', ItemViewSet)

Solution

1. Step 1: Recall the router method to register ViewSets

   The correct method to register a ViewSet with a router is register().

2. Step 2: Verify method names

   Methods like add(), include(), and attach() do not exist on routers for this purpose.

3. Final Answer:

   router.register('items', ItemViewSet) -> Option C

4. Quick Check:

   Use register() to add ViewSets to routers [OK]

Hint: Use router.register() to add ViewSets [OK]

Common Mistakes:

• Using non-existent router methods like add or include
• Confusing router registration with URL inclusion
• Forgetting to pass the ViewSet class

3. Given this code snippet, what URL patterns will be automatically created by the router?

from rest_framework import routers

router = routers.DefaultRouter()
router.register('books', BookViewSet)

medium

A. /books/list/ for list, /books/create/ for create

B. /books/viewset/ for all actions

C. /books/all/ for all actions

D. /books/ for list and create, /books/{pk}/ for retrieve, update, delete

Solution

1. Step 1: Understand DefaultRouter URL patterns

   DefaultRouter creates URLs like /books/ for listing and creating, and /books/{pk}/ for retrieve, update, and delete actions.

2. Step 2: Compare with other options

   Options A, C, and D use incorrect URL paths that are not generated by DefaultRouter automatically.

3. Final Answer:

   /books/ for list and create, /books/{pk}/ for retrieve, update, delete -> Option D

4. Quick Check:

   DefaultRouter creates standard REST URLs = B [OK]

Hint: DefaultRouter creates /resource/ and /resource/{id}/ URLs [OK]

Common Mistakes:

• Expecting custom URL suffixes like /list or /create
• Not knowing DefaultRouter auto-generates URLs
• Confusing URL patterns with manual URL configs

4. Identify the error in this router registration code:

from rest_framework import routers

router = routers.DefaultRouter()
router.register('authors', authorsViewSet)

medium

A. The ViewSet class name should be capitalized as AuthorsViewSet

B. The router should be SimpleRouter, not DefaultRouter

C. The register method requires a third argument for basename

D. The URL prefix 'authors' is invalid

Solution

1. Step 1: Check the ViewSet class name

   Python class names should be capitalized. 'authorsViewSet' is likely a typo and should be 'AuthorsViewSet'.

2. Step 2: Validate other options

   DefaultRouter is valid here, basename is optional if ViewSet has queryset, and 'authors' is a valid URL prefix.

3. Final Answer:

   The ViewSet class name should be capitalized as AuthorsViewSet -> Option A

4. Quick Check:

   Class names must be capitalized = A [OK]

Hint: Class names must start with uppercase letter [OK]

Common Mistakes:

• Using lowercase for class names
• Thinking basename is always required
• Confusing router types unnecessarily

5. You want to create a router that registers two ViewSets: ProductViewSet and CategoryViewSet. You also want to customize the basename for CategoryViewSet because it has no queryset attribute. Which code snippet correctly does this?

hard

A. router.register('products', ProductViewSet)
router.register('categories', CategoryViewSet)

B. router.register('products', ProductViewSet)
router.register('categories', CategoryViewSet, basename='category')

C. router.register('products', ProductViewSet, basename='product')
router.register('categories', CategoryViewSet)

D. router.register('products', ProductViewSet, basename='products')
router.register('categories', CategoryViewSet, basename=CategoryViewSet)

Solution

1. Step 1: Understand basename usage

   If a ViewSet lacks a queryset attribute, you must provide a basename when registering it with the router.

2. Step 2: Check the code snippets

   router.register('products', ProductViewSet) router.register('categories', CategoryViewSet, basename='category') correctly registers ProductViewSet without basename (assuming it has queryset) and CategoryViewSet with basename='category'. Other options either omit basename or misuse it.

3. Final Answer:

   router.register('products', ProductViewSet) router.register('categories', CategoryViewSet, basename='category') -> Option B

4. Quick Check:

   Provide basename if no queryset = C [OK]

Hint: Add basename if ViewSet has no queryset [OK]

Common Mistakes:

• Omitting basename for ViewSets without queryset
• Using wrong basename strings
• Adding basename unnecessarily