django-drf-cheatsheet.md

Django DRF Cheat Sheet

Django Rest Framework

Overview:

    http request --> url_route --> view --> serializer --> data-dict response

Flows

--> http request
    url_route (urls.py)
    view (views.py)    # adds context for serializer
    serializer (serializers.py)
    db (models.py)
<-- data-dict response

Create:  post   data-dict --(deserialize)--> Object
Update:  patch  id, data-dict --> new data
Delete:  delete id --> 
Get:     get    id --(serialize)--> data-dict
List:    get    --> list of data-dicts

Basics

Serialize:

  # Object -> dict
  s = Serializer(obj)
  s.data

Move from the raw form to python native dict.

Deserialize:

  # dict -> Object
  s = Serializer(data={..})
  s.is_valid()
  s.validated_data

Construct the Object from the python native parts and validate the parts (inputs) meet any requirements or format.

Validation:

  s = Serializer(data={..})
  if s.is_valid():
    s.validated_data
  else:
    s.errors  # dict(field=[problems..])

Views

    class SimpleView(APIView):
        def post(self, request, *args, **kws):
            request.data
            return Response(..)
            
        def get(self, request, *args, **kws):
            request.query_params
            ...
            
        def patch(self, request, *args, **kws):
            ...
            
        def delete(self, request, *args, **kws):
            ...

ViewSets

    class SimpleViewSet(ViewSet):  # ModelViewSet
        serializer_class = SimpleSerializer
        
        def create(self, request, *args, **kws):
            return Response(..)
            
        def update(self, request, *args, **kws):
        
        def partial_update(self, request, *args, **kws):
        
        def destroy(self, request, *args, **kws):
        
        def retrieve(self, request, *args, **kws):
        
        def list(self, request, *args, **kws):

More features.

    class SimpleViewSet(ViewSet):  # ModelViewSet
        serializer_class = SimpleSerializer
        lookup_field = 'field'
        authentication_classes = ()
        permissions_classes = ()
        
        def create(self, request, *args, **kws):
            ...

        def get_queryset(self):
            ...

Code Examples

Serializer

Model or class file

# simple.py
from datetime import datetime

class Simple:
    def __init__(self, name, email, created_at=None):
        self.name = name
        self.email = email
        self.created_at = created_at or datetime.utcnow()

    def save(self):
        # persist

Serializers file

# serializers.py
from rest_framework import serializers


class SimpleSerializer(serializers.Serializer):
    name = serializers.CharField(max_length=128)
    email = serializers.EmailField()
    created_at = serializers.DateTimeField()


# serialize
obj = Simple('Charles', 'charles@b2si.com')
serializer = SimpleSerializer(obj)  # obj becomes serializer.instance
print(serializer.data)  # -> data-dict {'name': 'Charles', 'email': 'charles@b2si.com', 'created_at': '2018-07-16T19:45:39.583565Z'}

from rest_framework.renderers import JSONRenderer

json = JSONRenderer().render(serializer.data)  # -> str


# deserialize
from django.utils.six import BytesIO
from rest_framework.parsers import JSONParser

stream = BytesIO(json)
data = JSONParser().parse(stream)

serializer = SimpleSerializer(data=data)  # data becomes available as serializer.initial_data
serializer.is_valid()  # -> bool

if is_valid:  # always check before using validated data
  serializer.validated_data  # -> data-dict {'name': 'Charles', 'email': 'charles@b2si.com', 'created_at': '2018-07-16T19:45:39.583565Z'}

else:
  serializer.errors  # explains what went wrong

#
# save()  # -> object: puts the data-dict to it's destination (db, email, class obj)
# -> create(validated_data)  # -> object: Model.objects.create()
# -> update(orig_object_instance, validated_data)  # -> object: model_object.foo = vdata['bar']; model_object.save()

Serializer Fields

Args

• read_only (False) in output, not allowed input,
• write_only (False) in create and update, not in output
• required (True) raise if not supplied for serialization
• allow_null (False) None is considered a valid value