Django REST Framework Part 1

"Serialize"는 모델 인스턴스나 QuerySet과 같은 데이터를 JSON 형식의 파일로 변환하는 작업 입니다.

"Deserialize"는 JSON 형식의 데이터를 정의된 포맷에 맞추어 다시 모델 인스턴스로 변환하는 작업 입니다.

"Serializer"는 형식을 변환하는 과정을 담당하는 매개체 입니다.

 

serializer 생성하기

polls_api/serializers.py

from rest_framework import serializers
from polls.models import Question

class QuestionSerializer(serializers.Serializer):
    id = serializers.IntegerField(read_only=True)
    question_text = serializers.CharField(max_length=200)
    pub_date = serializers.DateTimeField(read_only=True)

    def create(self, validated_data):
        return Question.objects.create(**validated_data)

    def update(self, instance, validated_data):
        instance.question_text = validated_data.get('question_text', instance.question_text)
        instance.save()
        return instance

 

 

Django Shell에서 Serializer 사용하기

polls_api/serializers.py

from rest_framework import serializers
from polls.models import Question

class QuestionSerializer(serializers.Serializer):
    id = serializers.IntegerField(read_only=True)
    question_text = serializers.CharField(max_length=200)
    pub_date = serializers.DateTimeField(read_only=True)

    def create(self, validated_data):
        return Question.objects.create(**validated_data)

    def update(self, instance, validated_data):
        instance.question_text = validated_data.get('question_text', instance.question_text) + '[시리얼라이저에서 업데이트]'
        instance.save()
        return instance

#Serialize
>>> from polls.models import Question
>>> from polls_api.serializers import QuestionSerializer
>>> q = Question.objects.first()
>>> q 
<Question: 제목: 휴가를 어디서 보내고 싶으세요?, 날짜: 2023-02-05 18:52:59+09:00>
>>> serializer = QuestionSerializer(q)
>>> serializer.data
{'id': 1, 'question_text': '휴가를 어디서 보내고 싶으세요?', 'pub_date': '2023-02-05T18:52:59Z'}
>>> from rest_framework.renderers import JSONRenderer
>>> json_str = JSONRenderer().render(serializer.data)
>>> json_str
b'{"id":1,"question_text":"\xed\x9c\xb4\xea\xb0\x80\xeb\xa5\xbc \xec\x96\xb4\xeb\x94\x94\xec\x84\x9c \xeb\xb3\xb4\xeb\x82\xb4\xea\xb3\xa0 \xec\x8b\xb6\xec\x9c\xbc\xec\x84\xb8\xec\x9a\x94?","pub_date":"2023-02-05T18:52:59Z"}'

# Deserialize
>>> import json
>>> data = json.loads(json_str)
>>> data
{'id': 1, 'question_text': '휴가를 어디서 보내고 싶으세요?', 'pub_date': '2023-02-05T18:52:59Z'}
>>> serializer = QuestionSerializer(data=data)
>>> serializer.is_valid()  
True
>>> serializer.validated_data 
OrderedDict([('question_text', '휴가를 어디서 보내고 싶으세요?')])
>>> new_question = serializer.save() # Create
>>> new_question
<Question: 제목: 휴가를 어디서 보내고 싶으세요?, 날짜: 2023-02-14 18:46:56.209215+00:00>
>>> data={'question_text': '제목수정'}
>>> serializer = QuestionSerializer(new_question, data=data) 
>>> serializer.is_valid()  
True
>>> serializer.save() # Update
<Question: 제목: 제목수정[시리얼라이저에서 업데이트], 날짜: 2023-04-25 13:15:05.852404+00:00>

#Validation이 통과하지 않는 경우
>>> long_text = "abcd"*300
>>> data = {'question_text':long_text}
>>> serializer = QuestionSerializer(data=data)
>>> serializer.is_valid()
False
>>> serializer.errors
{'question_text': [ErrorDetail(string='Ensure this field has no more than 200 characters.', code='max_length')]}

 

 

ModelSerializer

polls_api/serializers.py

from rest_framework import serializers
from polls.models import Question

class QuestionSerializer(serializers.ModelSerializer):
    class Meta:
        model = Question
        fields = ['id','question_text', 'pub_date']

>>> from polls_api.serializers import QuestionSerializer
>>> print(QuestionSerializer())
QuestionSerializer():
    id = IntegerField(read_only=True)
    question_text = CharField(max_length=200)
    pub_date = DateTimeField(read_only=True)
>>> serializer = QuestionSerializer(data={'question_text':'모델시리얼라이저로 만들어 봅니다.'})
>>> serializer.is_valid()
True
>>> serializer.save()
<Question: 제목: 모델시리얼라이저로 만들어 봅니다., 날짜: 2023-02-14 19:41:081444+00:00>

 

 

GET

polls_api/views.py

from polls.models import Question
from polls_api.serializers import QuestionSerializer
from rest_framework.response import Response
from rest_framework.decorators import api_view

@api_view()
def question_list(request):
    questions = Question.objects.all()
    serializer = QuestionSerializer(questions, many = True)
    return Response(serializer.data)

 

polls_api/urls.py

from django.urls import path
from .views import *

urlpatterns = [
    path('question/', question_list, name='question-list')
]

 

mysite/urls.py

from django.urls import include, path
from django.contrib import admin

urlpatterns = [
    path('admin/', admin.site.urls),
    path('polls/', include('polls.urls')),
    path('rest/', include('polls_api.urls')),
]

 

 

HTTP Methods

• Create : POST
• Get : GET
• Update : PUT
• Delete : DELETE

 

 

POST

polls_api/views.py

from rest_framework.decorators import api_view
from polls.models import Question
from polls_api.serializers import QuestionSerializer
from rest_framework.response import Response
from rest_framework import status

@api_view(['GET','POST'])
def question_list(request):
    if request.method == 'GET':
        questions = Question.objects.all()
        serializer = QuestionSerializer(questions, many = True)
        return Response(serializer.data)
    
    if request.method == 'POST':
        serializer = QuestionSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        else:
            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

 

 

PUT/DELETE

polls_api/views.py

from django.shortcuts import get_object_or_404

@api_view(['GET', 'PUT', 'DELETE'])
def question_detail(request, id):
    question = get_object_or_404(Question, pk=id)
    
    if request.method == 'GET':
        serializer = QuestionSerializer(question)
        return Response(serializer.data)

    if request.method == 'PUT':
        serializer = QuestionSerializer(question, data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_200_OK)
        else:    
            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    if request.method == 'DELETE':
        question.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)

 

polls_api/urls.py

from django.urls import path
from .views import *

urlpatterns = [
    path('question/', question_list, name='question-list'),
    path('question/<int:id>/', question_detail, name='question-detail')
]

 

 

Class 기반의 뷰(Views)

polls_api/views.py

from rest_framework.views import APIView

class QuestionList(APIView):
    def get(self, request):
        questions = Question.objects.all()
        serializer = QuestionSerializer(questions, many=True)
        return Response(serializer.data)

    def post(self, request):
        serializer = QuestionSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

class QuestionDetail(APIView):
    def get(self, request, id):
        question = get_object_or_404(Question, pk=id)
        serializer = QuestionSerializer(question)
        return Response(serializer.data)

    def put(self, request, id):
        question = get_object_or_404(Question, pk=id)
        serializer = QuestionSerializer(question, data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_200_OK)
        else:    
            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
        
    def delete(self, request, id):
        question = get_object_or_404(Question, pk=id)
        question.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)

 

polls_api/urls.py

from django.urls import path
from .views import *

urlpatterns = [
    path('question/', QuestionList.as_view(), name='question-list'),
    path('question/<int:id>/', QuestionDetail.as_view(), name='question-detail'),
]

 

 

Mixin

polls_api/views.py

from polls.models import Question
from polls_api.serializers import QuestionSerializer
from rest_framework import mixins
from rest_framework import generics

class QuestionList(mixins.ListModelMixin,
                  mixins.CreateModelMixin,
                  generics.GenericAPIView):
    queryset = Question.objects.all()
    serializer_class = QuestionSerializer

    def get(self, request, *args, **kwargs):
        return self.list(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        return self.create(request, *args, **kwargs)

class QuestionDetail(mixins.RetrieveModelMixin,
                    mixins.UpdateModelMixin,
                    mixins.DestroyModelMixin,
                    generics.GenericAPIView):
    queryset = Question.objects.all()
    serializer_class = QuestionSerializer

    def get(self, request, *args, **kwargs):
        return self.retrieve(request, *args, **kwargs)

    def put(self, request, *args, **kwargs):
        return self.update(request, *args, **kwargs)

    def delete(self, request, *args, **kwargs):
        return self.destroy(request, *args, **kwargs)

 

 

polls_api/urls.py

from django.urls import path
from .views import *

urlpatterns = [
    path('question/', QuestionList.as_view(), name='question-list'),
    path('question/<int:pk>/', QuestionDetail.as_view(), name='question-detail'),
]

 

 

Generic API View

polls_api/views.py

from polls.models import Question
from polls_api.serializers import QuestionSerializer
from rest_framework import generics

class QuestionList(generics.ListCreateAPIView):
    queryset = Question.objects.all()
    serializer_class = QuestionSerializer

class QuestionDetail(generics.RetrieveUpdateDestroyAPIView):
    queryset = Question.objects.all()
    serializer_class = QuestionSerializer