By Emmanuelle Delescolle and Leila Verhaegen

@EmmaDelescolle
@LeilaVerhaegen
LevIT

Django REST Framework

Hit the ground running with your

API

Who are we?

  • Co-founders of LevIT
  • Small Belgian company
  • Django and Ember remote consulting
  • OpenSource libararies authors

Getting your computer ready for the workshop

Please, follow the instructions on http://bit.ly/drf_cc

Slides at http://bit.ly/htgr_drf

Code at http://bit.ly/htgr_drf_commits

sudo pip install cookiecutter

Docker container?

If you have trouble getting your computer up and running, you can try the docker image here under.

We also have a couple bootable USB sticks

git clone https://bitbucket.org/levit_scs/djangoconeu2018.git
cd djangoconeu2018
sudo docker-compose run web

Getting started with a CookieCutter

$ cookiecutter https://bitbucket.org/levit_scs/cc_htgr_drf.git
Cloning into 'cc_htgr_drf'...
remote: Counting objects: 407, done.
remote: Compressing objects: 100% (296/296), done.
remote: Total 407 (delta 202), reused 189 (delta 75)
Receiving objects: 100% (407/407), 58.77 KiB | 0 bytes/s, done.
Resolving deltas: 100% (202/202), done.
Checking connectivity... done.
project_name [Project name]: My Webshop
repo_name [my_webshop]: 
author [Your Name]: Emma
username [emma]: 
email [you@domain.com]: 
python [python3.6]: 
create_superuser [no]: yes

Start things up

$ ./run.sh

In shell, launch Django with

Windows user other than Windows 10 Pro, please raise your hand

What did we install?

  • Django
  • Django Rest Framework
  • Django Filter
  • Django CORS headers
  • DRF-Schema-Adapter

Django REST Framework

  • Build Serializer
  • Build ViewSet's
  • Build EndPoints (urls) through routers

Used to:

Documentation:

Django Filter

Used to easily create filters with DRF

Django CORS header

Used to allow access to Django from another domain

https://django-filter.readthedocs.io/
https://github.com/ottoyiu/django-cors-headers

DRF-Schema-Adapter

An extra layer on top of Django REST Framework to facilitate creating endpoints the way you would create Django Admin classes

Documentation on Read The Docs

DRF-Schema-Adapter is also useful to close the bridge between your backend and your frontend and do things like exporting your serializers and viewsets definitions to frontend models or helper so that you don't have to do convert them manually.

(This feature will not be covered by this workshop)

Let's look at what has been created for us

Regular ViewSet and Serializer

# my_webshop/views.py

class UserViewSet(ModelViewSet):                                                                     
                                                                                                     
    serializer_class = UserSerializer                                                                
    queryset = get_user_model().objects.all()                                                        
    filter_backends = (DjangoFilterBackend, )                                                        
    filter_fields = ('first_name', 'last_name')
# my_webshop/serializers.py

class UserSerializer(serializers.ModelSerializer):                                                   
                                                                                                     
    class Meta:                                                                                      
        model = get_user_model()                                                                     
        fields = (                                                                                   
            'id',                                                                                    
            'username',                                                                              
            'email',                                                                                 
            'first_name',                                                                            
            'last_name'                                                                              
        )

Catalog application

$ ./manage.py startapp catalog
INSTALLED_APPS = (
    ...
    'catalog',
)

In your venv-activated shell

settings.py

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*All commands should be run in a "venv-activated" shell.
To activate a venv, from the back directory, run





You will know that you are in a venv-activated shell because your prompt will be prefixed with (venv) or [venv] depending on your computer.

$ source ../venv/bin/activate

Models

For this workshop we will be creating 2 models: Product and Category

from django.db import models


class Category(models.Model):
    
    name = models.CharField(max_length=255)
    
    def __str__(self):
        return self.name


class Product(models.Model):
    
    name = models.CharField(max_length=255)
    category = models.ForeignKey(Category, related_name='products', on_delete=models.CASCADE)
    description = models.TextField()
    image = models.URLField()
    price = models.DecimalField(max_digits=6, decimal_places=2)
    likes = models.SmallIntegerField(default=0)
    views = models.PositiveSmallIntegerField(default=0)

    def __str__(self):
        return self.name

catalog/models.py

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Models

$ ./manage.py makemigrations
Migrations for 'catalog':
  0001_initial.py:
    - Create model Category
    - Create model Product
$ ./manage.py migrate
Operations to perform:
  Apply all migrations: auth, sessions, catalog, kombu_transport_django,
admin, contenttypes
Running migrations:
  Rendering model states... DONE
  Applying catalog.0001_initial... OK

in your venv-activated shell

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ModelAdmins

from django.contrib import admin

from .models import Category, Product


admin.site.register(Category)
admin.site.register(Product)

catalog/admin.py

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Endpoints

(Think of them as Django admin classes) We will be creating one for each model

from drf_auto_endpoint.router import router
from .models import Category, Product


router.register(Category)
router.register(Product)

catalog/endpoints.py

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🎉 We now have a fully functional API 🎉

In your browser on http://localhost:8000/api/v1/.

(You may need to restart your Django server)

Customizing Endpoints

(still very similar to Django admin classes)

from drf_auto_endpoint.endpoints import Endpoint
from drf_auto_endpoint.router import register

from .models import Category, Product


@register
class ProductEndpoint(Endpoint):

    model = Product
    read_only = True
    search_fields = ('name', )
    filter_fields = ('category_id', )
    ordering_fields = ('price', 'name', )


@register
class CategoryEndpoint(Endpoint):

    model = Category
    search_fields = ('name', )
    read_only = True

catalog/endpoints.py

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Customizing ViewSets

from rest_framework import viewsets

from .models import Category, Product


class ProductViewSet(viewsets.ReadOnlyModelViewSet):

    def retrieve(self, request, *args, **kwargs):
        obj = self.get_object()
        obj.views += 1
        obj.save()
        return super(ProductViewSet, self).retrieve(request, *args, **kwargs)

catalog/views.py

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...
from .views import ProductViewSet
...


@register
class ProductEndpoint(Endpoint):

    ...
    base_viewset = ProductViewSet

catalog/endpoints.py

Customizing Serializers

from rest_framework import serializers

from .models import Category, Product


class SimpleCategorySerializer(serializers.ModelSerializer):

    class Meta:
        model = Category
        fields = ('id', 'name', )


class ProductSerializer(serializers.ModelSerializer):

    category = SimpleCategorySerializer()

catalog/serializers.py

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...
from .serializers import ProductSerializer
...


@register
class ProductEndpoint(Endpoint):

    ...
    base_serializer = ProductSerializer

catalog/endpoints.py

Customizing Serializers

Made Simple

from drf_auto_endpoint.factories import serializer_factory
from rest_framework import serializers

from .models import Category


class ProductSerializer(serializers.ModelSerializer):

    category = serializer_factory(model=Category, fields=('id', 'name'))()

catalog/serializers.py

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Using different serializers

for different actions

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from drf_auto_endpoint.factories import serializer_factory

from .serializers import ProductSerializer
...


class ProductViewSet(viewsets.ReadOnlyModelViewSet):

    ...

    def get_serializer_class(self):
        if getattr(self, 'action', None) == 'retrieve':
            return serializer_factory(self.endpoint, base_class=ProductSerializer)
        return super(ProductViewSet, self).get_serializer_class()

catalog/views.py

catalog/endpoints.py

...

@register
class ProductEndpoint(Endpoint):

    ...
    # base_Serializer = ProductSerializer

🎉 We now have a fully customized CRUD API 🎉

Can we go beyond CRUD?

Actions

Simple "detail" action

from django.shortcuts import get_object_or_404

from drf_auto_endpoint.decorators import custom_action

from rest_framework.response import Response
...

@register
class ProductEndpoint(Endpoint):

    ...
    @custom_action(method='POST')
    def like(self, request, pk):
        obj = get_object_or_404(self.model, pk=pk)
        obj.likes += 1
        obj.save()
        return Response(self.get_serializer(obj).data)

catalog/endpoints.py

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Actions

from drf_auto_endpoint.decorators import custom_action, wizard

from .serializers import LikeCountSerializer
...

@register
class ProductEndpoint(Endpoint):

    ...
    @wizard(LikeCountSerializer)
    def dislike(self, request, pk):
        obj = get_object_or_404(self.model, pk=pk)
        obj.likes -= request.validated_data['amount']
        obj.save()
        return Response(self.get_serializer(obj).data)

catalog/endpoints.py

...

class LikeCountSerializer(serializers.Serializer):
    amount = serializers.IntegerField(min_value=1)

    class Meta:
        fields = ('amount', )

catalog/serializers.py

"detail" action with input data

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Actions

Simple "list" action

from drf_auto_endpoint.decorators import bulk_action, custom_action, wizard

...

@register
class ProductEndpoint(Endpoint):

    ...
    @bulk_action(method='POST')
    def reset_likes(self, request):
        self.model.objects.all().update(likes=0)
        return Response(status=204)

catalog/endpoints.py

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Actions

"list" action with input data

from django.db.models import F
...

@register
class ProductEndpoint(Endpoint):

    ...
    @wizard(LikeCountSerializer, meta_type='list')
    def cheatlikes(self, request):
        self.model.objects.all().update(
            likes=F('likes') + request.validated_data['amount']
        )
        return Response(status=204)

catalog/endpoints.py

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🎉 We now have a fully customized API 🎉

Questions?

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