基于Mixin扩展类和GenericAPIView实现接口

10.1 扩展类简介

(1）ListModelMixin

列表视图扩展类，提供list(request, *args, **kwargs)方法快速实现列表视图，返回200状态码。

该Mixin的list方法会对数据进行过滤和分页。

源代码：

class ListModelMixin(object):
    """
    List a queryset.
    """
    def list(self, request, *args, **kwargs):
        # 过滤
        queryset = self.filter_queryset(self.get_queryset())
        # 分页
        page = self.paginate_queryset(queryset)
        if page is not None:
            serializer = self.get_serializer(page, many=True)
            return self.get_paginated_response(serializer.data)
        # 序列化
        serializer = self.get_serializer(queryset, many=True)
        return Response(serializer.data)

(2）CreateModelMixin

创建视图扩展类，提供create(request, *args, **kwargs)方法快速实现创建资源的视图，成功返回201状态码。

如果序列化器对前端发送的数据验证失败，返回400错误。

源代码：

class CreateModelMixin(object):
    """
    Create a model instance.
    """
    def create(self, request, *args, **kwargs):
        # 获取序列化器
        serializer = self.get_serializer(data=request.data)
        # 验证
        serializer.is_valid(raise_exception=True)
        # 保存
        self.perform_create(serializer)
        headers = self.get_success_headers(serializer.data)
        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)

    def perform_create(self, serializer):
        serializer.save()

    def get_success_headers(self, data):
        try:
            return {'Location': str(data[api_settings.URL_FIELD_NAME])}
        except (TypeError, KeyError):
            return {}

(3） RetrieveModelMixin

详情视图扩展类，提供retrieve(request, *args, **kwargs)方法，可以快速实现返回一个存在的数据对象。

如果存在，返回200， 否则返回404。

源代码：

class RetrieveModelMixin(object):
    """
    Retrieve a model instance.
    """
    def retrieve(self, request, *args, **kwargs):
        # 获取对象，会检查对象的权限
        instance = self.get_object()
        # 序列化
        serializer = self.get_serializer(instance)
        return Response(serializer.data)

(4）UpdateModelMixin

更新视图扩展类，提供update(request, *args, **kwargs)方法，可以快速实现更新一个存在的数据对象。

同时也提供partial_update(request, *args, **kwargs)方法，可以实现局部更新。

成功返回200，序列化器校验数据失败时，返回400错误。

源代码：

class UpdateModelMixin(object):
    """
    Update a model instance.
    """
    def update(self, request, *args, **kwargs):
        partial = kwargs.pop('partial', False)
        instance = self.get_object()
        serializer = self.get_serializer(instance, data=request.data, partial=partial)
        serializer.is_valid(raise_exception=True)
        self.perform_update(serializer)

        if getattr(instance, '_prefetched_objects_cache', None):
            # If 'prefetch_related' has been applied to a queryset, we need to
            # forcibly invalidate the prefetch cache on the instance.
            instance._prefetched_objects_cache = {}

        return Response(serializer.data)

    def perform_update(self, serializer):
        serializer.save()

    def partial_update(self, request, *args, **kwargs):
        kwargs['partial'] = True
        return self.update(request, *args, **kwargs)

(5）DestroyModelMixin

删除视图扩展类，提供destroy(request, *args, **kwargs)方法，可以快速实现删除一个存在的数据对象。

成功返回204，不存在返回404。

源代码：

class DestroyModelMixin(object):
    """
    Destroy a model instance.
    """
    def destroy(self, request, *args, **kwargs):
        instance = self.get_object()
        self.perform_destroy(instance)
        return Response(status=status.HTTP_204_NO_CONTENT)

    def perform_destroy(self, instance):
        instance.delete()

10.2 快速实现五个接口

视图

"""
使用drf内置的模型扩展类(混入类)结合GenericAPIView快速实现五个接口
from rest_framework.mixins import ListModelMixin      获取多条数据，返回响应结果
from rest_framework.mixins import CreateModelMixin    添加一条数据，返回结果
from rest_framework.mixins import RetrieveModelMixin  获取一条数据，返回结果
from rest_framework.mixins import UpdateModdelMixin   更新一条数据返回结果
from rest_framework.mixins import DestroyModelMixin   删除一条数据，返回结果
"""
from app.models import studentsInfo
from .serializers import StudentModelSerializer
from rest_framework.generics import GenericAPIView
from rest_framework.mixins import ListModelMixin, CreateModelMixin, RetrieveModelMixin, UpdateModelMixin, \
    DestroyModelMixin


class StudentGenericAPIViewMixin(GenericAPIView, ListModelMixin, CreateModelMixin):
    queryset = studentsInfo.objects.all()
    serializer_class = StudentModelSerializer

    def get(self, request):
        """获取多条数据"""
        return self.list(request)

    def post(self, request):
        """添加一条数据"""
        return self.create(request)


class StudentGenericAPIViewMixin2(GenericAPIView, RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin):
    queryset = studentsInfo.objects.all()
    serializer_class = StudentModelSerializer

    def get(self, request, pk):
        """获取一条数据"""
        return self.retrieve(request, pk=pk)

    def put(self, request, pk):
        """更新一条数据"""
        return self.update(request, pk=pk)

    def delete(self, request, pk):
         """删除一条数据"""
        return self.destroy(request, pk=pk)

路由

from django.urls import path, re_path
from . import views

urlpatterns = [
    # APIView
    path('students/', views.StudentView.as_view()),
    re_path(r'^students/(?P<pk>\d+)/$', views.StudentAPIView.as_view()),

    # GenericAPIView
    path('students2/', views.StudentGenericAPIView.as_view()),
    re_path(r'^students2/(?P<pk>\d+)/$', views.StudentGenericAPIView2.as_view()),

    # GenericAPIView和mixin
    path('students3/', views.StudentGenericAPIViewMixin.as_view()),
    re_path(r'^students3/(?P<pk>\d+)/$', views.StudentGenericAPIViewMixin2.as_view())