Django-rest-framework中的五种 ModelMixin 类详解

一. 创建数据类 CreateModelMixin ：

class CreateModelMixin:
    """
    1. 接收前台数据，前天的序列化对象，request.data是 QueryDict
    如：
    2. 验证序列化数据的有效性
    3. 保存数据
    4. 获得请求头
    5. 返回状态
    Create a model instance.
    """
    def create(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        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 {}

 

二。返回所有数据列表 ListModelMixin：

class ListModelMixin:
    """
    1. 获取 queryset ，通过 filter_queryset 进行过滤筛选
    2. 对过滤筛选后的 queryset 进行分页，返回分页对象
    3. 序列化，并返回序列化的数据
    传入一个queryset，分别过滤，分页，序列化
    List a queryset.
    """
    def list(self, request, *args, **kwargs):
        queryset = self.filter_queryset(self.get_queryset())

        # 分页
        page = self.paginate_queryset(queryset)

        # 这个是分页的序列化
        if page is not None:
            serializer = self.get_serializer(page, many=True)
            # 下面是分页返回的额外结果
            return self.get_paginated_response(serializer.data)

        # 这个是不分页的序列化
        serializer = self.get_serializer(queryset, many=True)
        return Response(serializer.data)

 

三。传入参数，返回某个数据对象 RetrieveModelMixin:

class RetrieveModelMixin:
    """
    获取对象，序列化
    Retrieve a model instance.
    """
    def retrieve(self, request, *args, **kwargs):
        instance = self.get_object()
        serializer = self.get_serializer(instance)
        return Response(serializer.data)

四。 传入参数，更新数据对象 UpdateModelMixin:

class UpdateModelMixin:
    """
    更新：
    1. 获取 kwargs 字典中 partial 的值，如果没有，则返回False，有，则返回值
    2. 获取单个对象
    3. 通过序列化，获取单个对象的序列化对象
    4. 判断序列化对象的有效性
    5. 更新数据
    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)

 

五。传入参数，删除某个数据对象 DestroyModelMixin

class DestroyModelMixin:
    """
    删除：
    1. 获取单个对象
    2. 删除对象
    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()