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Vicente Antonio G. Reyes
Vicente Antonio G. Reyes

Posted on • Updated on • Originally published at vicentereyes.org

Getting started with Django Rest Framework

Photo by Markus Spiske: https://www.pexels.com/photo/a-laptop-screen-with-text-4439901/

In this article, we'll create a project that posts about rants using Django and Django Rest Framework. We'll use Django's built-in slugify method and override its save() method to automatically create a slug for each rant. We'll also use a third-party package called drf-writable-nested to handle the serialization of a ManyToManyField in the model.

We'll start by creating a virtual environment, installing the initial packages, creating the django project, creating the django app and finally doing the initial migrations

python -m venv venv
. venv/bin/activate
python -m pip install django djangorestframework
django-admin startproject myproject
cd myproject
python -m manage startapp rants
python -m manage migrate
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We list rest_framework and our rants app in the INSTALLED_APPS settings of our project and include them in the project urls.py

# settings.py
INSTALLED_APPS = [
    ...
    'rest_framework',
    'rants',
]

# myproject/urls.py
from django.urls import path, include

urlpatterns = [
    path('', include('rants.urls', namespace='main')),
    path('api-auth/', include('rest_framework.urls', namespace='rest_framework')),
]
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Next we create the models inside the rants app:

# models.py
from django.db import models


class Category(models.Model):
    title = models.CharField(max_length=50)
    slug = models.SlugField(max_length=50)

    def __str__(self):
        return self.title


class Rant(models.Model):
    title = models.CharField(max_length=150)
    slug = models.SlugField(max_length=150)
    categories = models.ManyToManyField(
        Category, related_name='rants_categories')

    class Meta:
        verbose_name = "rant"
        verbose_name_plural = 'rants'

    def __str__(self):
        return self.title

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We have a Rant model with a title, slug with a CharField and a categories field with a ManyToManyField connected to a Category model with a title and a slug field.

Then we migrate the database python -m manage makemigrations && python -m manage migrate. Next, we create a serializer for both models:

# serializers.py
from rest_framework import serializers
from .models import Rant, Category


class CategorySerializer(serializers.ModelSerializer):
    slug = serializers.SlugField(read_only=True)

    class Meta:
        model = Category
        fields = "__all__"


class RantSerializer(serializers.ModelSerializer):
    categories = CategorySerializer(many=True)
    slug = serializers.SlugField(read_only=True)


    class Meta:
        model = Rant
        fields = ('id', 'title', 'slug', 'categories')
        many = True
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Finally, we create our views and map it to our urls so we can see the API endpoints of our app.

# views.py
from rest_framework.response import Response
from rest_framework.generics import ListCreateAPIView, UpdateAPIView, DestroyAPIView

from .models import Rant
from .serializers import RantSerializer

class RantList(ListCreateAPIView):
    queryset = Rant.objects.all()
    serializer_class = RantSerializer

    def list(self, request):
        queryset = self.get_queryset()
        serializer = RantSerializer(queryset, many=True)
        return Response(serializer.data)


class RantUpdate(UpdateAPIView):
    queryset = Rant.objects.all()
    serializer_class = RantSerializer


class RantDelete(DestroyAPIView):
    queryset = Rant.objects.all()
    serializer_class = RantSerializer
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We use ListCreateAPIView for read-write endpoints to represent a collection of model instances which provide a get and post method handler, UpdateAPIView for update-only endpoints of a single model instance which provides a put and patch method handler, DestroyAPIView for a delete-only endpoint of a single model instance which provides a delete method handler. Let's map these views to the urls.py

# urls.py
from django.urls import path

from .views import RantList, RantUpdate, RantDelete
from .models import Rant
from .serializers import RantSerializer

app_name = 'rants'


urlpatterns = [
    path('api/rants/', RantList.as_view(queryset=Rant.objects.all(), serializer_class=RantSerializer)),
    path('api/rants/update/<int:pk>/', RantUpdate.as_view(queryset=Rant.objects.all(), serializer_class=RantSerializer)),
    path('api/rants/delete/<int:pk>/', RantDelete.as_view(queryset=Rant.objects.all(), serializer_class=RantSerializer)),
]
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We can now view the api endpoints in the browser using the drf package but I personally prefer to see the api endpoints using another package which is the drf-yasg package. Let's install and configure the package:

python -m pip install drf-yasg

# settings.py
INSTALLED_APPS = [
    ....
    'rest_framework',
    'drf_yasg',
]
# urls.py
from django.urls import path, include
from rest_framework import permissions
from drf_yasg.views import get_schema_view
from drf_yasg import openapi

schema_view = get_schema_view(
   openapi.Info(
      title="Rants API",
      default_version='v1',
      description="Rants",
      terms_of_service="https://www.google.com/policies/terms/",
      contact=openapi.Contact(email="contact@snippets.local"),
      license=openapi.License(name="BSD License"),
   ),
   public=True,
   permission_classes=[permissions.AllowAny],
)
urlpatterns = [path('api/', schema_view.with_ui('swagger', cache_timeout=0), name='schema-swagger-ui'),]
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Now we run python -m manage runserver and head over to http://localhost:8000/api/ to see what we've created

Rants API screenshot

But we have a problem, the categories field has an error despite inputting a str in the field.

{
  "categories": [
    "Expected a list of items but got type \"str\"."
  ]
}
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To solve this we'll install drf-nested-writable in our app to serialize the categories field then update the serializers.py file to include WritableNestedModelSerializer in our RantSerializer

python -m pip install drf-nested-writable

# serializers.py
from drf_writable_nested.serializers import WritableNestedModelSerializer


class RantSerializer(WritableNestedModelSerializer):
    categories = CategorySerializer(many=True)
    slug = serializers.SlugField(read_only=True)

    class Meta:
        model = Rant
        fields = ('id', 'title', 'slug', 'categories')
        many = True
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Now when we add new data for our app using the rants_create endpoint, we won't get the error we got above anymore but instead. We also override the save() method in our models for the slug field to automatically fill the database in

Rants API

The code to override the save() method in our models

# models.py
...
from django.utils.text import slugify

...
    def save(self, *args, **kwargs):
        self.slug = slugify(self.title)
        super(Category, self).save(*args, **kwargs)
        return self.slug

...
    def save(self, *args, **kwargs):
        self.slug = slugify(self.title)
        super(Rant, self).save(*args, **kwargs)
        return self.slug
...
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Conclusion:
This took me a while to solve since I'm at GMT+8 but hey, at least it got solved and I learned how to override the save method in the models and learned about the drf-writable-nested package to fix my issue.

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