DRF返回值源码分析

1 返回值

• 在视图中定义finalize_response方法（也可以用来判断是否异常）

• 自定义异常

  • 配置文件

    # settings.py
    REST_FRAMEWORK = {
        "EXCEPTION_HANDLER": 'utils.handlers.exception_handler'		# 自定义的exceptional_handler路径
    }
    

  • 在exceptional_handler函数中做自定义

1.1 正常返回

from rest_framework.views import APIView
from rest_framework.request import Request
from rest_framework.response import Response


class DemoView(APIView):

    def get(self, request: Request):
        return Response({"name": "张三", "age": 22})

    def finalize_response(self, request, response, *args, **kwargs):
        response = super().finalize_response(request, response, *args, **kwargs)

        # 对数据进行改造
        response.data = {"code": 0, "data": response.data}
        return response

1.2 异常返回

自定义exception_handler

utils/handlers.py

from django.http import Http404

from rest_framework import exceptions
from rest_framework.response import Response
from rest_framework.exceptions import ValidationError
from rest_framework.exceptions import Throttled
from rest_framework.exceptions import PermissionDenied
from rest_framework.exceptions import NotAuthenticated
from rest_framework.exceptions import AuthenticationFailed
from rest_framework.views import set_rollback


def exception_handler(exc, context):
    if isinstance(exc, Http404):
        exc = exceptions.NotFound()
        exc.ret_code = 1001
    elif isinstance(exc, PermissionDenied):
        exc = exceptions.PermissionDenied()
        exc.ret_code = 1002
    elif isinstance(exc, (AuthenticationFailed, NotAuthenticated)):
        exc.ret_code = 1003
    elif isinstance(exc, Throttled):
        exc.ret_code = 1004
    elif isinstance(exc, ValidationError):
        exc.ret_code = 1005

    # 处理drf相关的异常
    if isinstance(exc, exceptions.APIException):
        headers = {}
        if getattr(exc, 'auth_header', None):
            headers['WWW-Authenticate'] = exc.auth_header
        if getattr(exc, 'wait', None):
            headers['Retry-After'] = '%d' % exc.wait

        if isinstance(exc.detail, (list, dict)):
            data = exc.detail
        else:
            code = getattr(exc, 'ret_code', None) or -1
            data = {'code': code, 'detail': exc.detail}

        set_rollback()
        return Response(data, status=exc.status_code, headers=headers)
    return None

utils/exceptions.py

from rest_framework import exceptions


class ExtraException(exceptions.APIException):
    def __init__(self, detail=None, ret_code=None, code=None):
        super().__init__(detail, code)
        self.ret_code = ret_code

views.py

from rest_framework import exceptions
from rest_framework import serializers
from rest_framework.viewsets import GenericViewSet
from rest_framework.mixins import ListModelMixin
from rest_framework.mixins import CreateModelMixin, RetrieveModelMixin, DestroyModelMixin, UpdateModelMixin
from rest_framework.authentication import BaseAuthentication
from rest_framework.permissions import BasePermission
from rest_framework.throttling import BaseThrottle

from api import models
from utils.exceptions import ExtraException


class ExtraAuthentication(BaseAuthentication):
    def authenticate(self, request):
        raise exceptions.AuthenticationFailed("认证失败")

    def authenticate_header(self, request):
        return "api"


class ExtraPermission(BasePermission):
    def has_permission(self, request, view):
        return False

    def has_object_permission(self, request, view, obj):
        return False


class ExtraThrottle(BaseThrottle):
    def allow_request(self, request, view):
        return False


class DemoSerializer(serializers.ModelSerializer):
    class Meta:
        model = models.UserInfo
        fields = "__all__"


class DemoView(ListModelMixin, CreateModelMixin, RetrieveModelMixin, DestroyModelMixin, UpdateModelMixin,
               GenericViewSet):
    # authentication_classes = [ExtraAuthentication]
    # throttle_classes = [ExtraThrottle]
    # permission_classes = [ExtraPermission]
    queryset = models.UserInfo.objects.all()
    serializer_class = DemoSerializer

    def perform_create(self, serializer):
        self.dispatch
        if True:
            # 自定义错误
            # raise ExtraException("数据异常")
            raise ExtraException("更新失败", ret_code=9000)
        serializer.save()

    def finalize_response(self, request, response, *args, **kwargs):
        response = super().finalize_response(request, response, *args, **kwargs)
        if response.exception:
            return response

        response.data = {'code': 0, 'data': response.data}
        return response

1.3 drf返回值机制源码