REST framework(视图与视图组件)

一、APIView的简单使用

　　一个简单的序列化器：

from rest_framework.exceptions import ValidationError
class BookSerialize(serializers.ModelSerializer):
    class Meta:
        model = models.Author
        fields = '__all__'  # 索取数据库定义的所有字段，一般不用所有字段
        # 获取指定字段
        # fields = ("id","name")

　　视图的数据创建：

　　is_valid()与save()方法：这里实例化对象都是序列化器产生，调用的都是序列化器的父类方法

# 视图层
from rest_framework.views import APIView
from rest_framework.response import Response

class Books(APIView):
   
    def post(self, request):   # 添加一条数据
         print( request.data )
    
        response = {"status": 100, "msg": "插入成功"}
        try:
            book_ser = BookSerialize(data=request.data)
            if book_ser.is_valid():    # 数据校验，查看钩子源码入口 is_valid 进入
                book_ser.save()   # 修改数据库
                response['data'] = book_ser.data
            else:
                response['msg'] = book_ser.errors  # 错误信息
        except Exception as e:
            response['msg'] = str(e)
        return Response(response)

二、APIView的常见使用方法

　　2.1 不需要指定PK的视图方法：

　　get请求：获取所有数据，many=True

　　post:创建一条新数据

　　put:更新全部记录

from app01.myserialize import BookSerialize
from rest_framework.response import Response
from rest_framework.views import APIView

class Books(APIView):
    # get请求 查所有
    def get(self, request, *args, **kwargs):
        response = {"status": 100, "msg": "查看所有"}

        all_book = Book.objects.all()
        ser = BookSerialize(all_book, many=True)
        response["data"] = ser.data   # 序列化以后的数据在data里
        return Response(response)
    
    # post请求 添加数据
    def post(self, request):
        response = {"status": 100, "msg": "插入成功"}
        try:
            book_ser = BookSerialize(data=request.data)
            if book_ser.is_valid():
                book_ser.save()
                response['data'] = book_ser.data
            else:
                response['msg'] = book_ser.errors
        except Exception as e:
            response['msg'] = str(e)
        return Response(response)

　　2.2 需要指定PK值的某一条数据操作：

　　get:获取单条记录，many=False

　　patch:更新某一条记录数据

　　delete:删除某一条数据

from app01.myserialize import BookSerialize
from rest_framework.response import Response
from rest_framework.views import APIView

class BookView(APIView):
    #  get请求 查看一条数据
    def get(self, request, pk, *args, **kwargs):
        response = {"status": 100, "msg": "查看单条"}
        book = Book.objects.filter(nid=pk).first()
        ser = BookSerialize(book, many=False)
        response["data"] = ser.data  # 序列化以后的数据在data里
        return Response(response)
        
    # delete请求 删除数据
    def delete(self, request, pk, *args, **kwargs):
        Book.objects.filter(nid=pk).delete()
        return Response("")
    
    # patch请求  更新数据
    def put(self, request, pk):
        response = {"status": 100, "msg": "修改成功"}
        book_obj = Book.objects.filter(nid=pk).first()
        book_ser = BookSerialize(data=request.data, instance=book_obj)  # 反序列化，指定要修改的数据库
        if book_ser.is_valid():
            book_ser.save()  # 修改数据库( rest_framework封装了代码 )
            response["data"] = book_ser.data
        else:
            response["error"] = book_ser.error_messages
        return Response(response)

三、分页与排序

　　request.query_params 中可以获取?param1=32&param2=23形式的参数.

class SurveysApi(ModelViewSet):
    pass
    """
    获取一组数据需要什么?

        1, model
        2, 序列化器
    """
    queryset = models.Survey.objects.all()
    # 实例化一个自定义的序列化器
    serializer_class = basic.SurveySerializer

    # 过滤器，循环for实例化filter_backends，在调用filter_queryset()方法实现过滤
    # 每个filter_queryset()方法在各自的类中SearchFilter/OrderingFilter/CustomFilter
    filter_backends = (filters.SearchFilter, filters.OrderingFilter, CustomFilter,)
    # 配合 filters.SearchFilter 使用, 如果想支持更多的字段搜索, 添加字段名称即可
    search_fields = ("grade__name",)
    # 配合 filters.OrderingFilter 使用, 如果想支持更多的字段排序, 添加字段名称即可
    ordering_fields = ("grade__name",)

    # 分页器
    # 定义分页器类
    pagination_class = pagination.LimitOffsetPagination

    # 表字段
    table_column = [
        {
            "prop": "grade",
            "label": "问卷班级"
        },
        {
            "prop": "times",
            "label": "第几次"
        },
    ]

    # 重写父类的list方法
    def list(self, request, *args, **kwargs):
        # self.get_queryset()获取queryset值
        queryset = self.filter_queryset(self.get_queryset())

        # 帮助实现分页的代码
        page = self.paginate_queryset(queryset)
        if page is not None:
            serializer = self.get_serializer(page, many=True)
            """
            'request': self.request,
            'format': self.format_kwarg,
            'view': self
            """
            # 重写自定义get_paginated_response方法，实现自定义字段的排序
            return self.get_paginated_response(serializer.data)

        # 无分页情况
        serializer = self.get_serializer(queryset, many=True)

        return Response(
            {
                "code": 0,
                "data": {
                    "table_column": self.table_column,
                    "table_data": serializer.data
                }
            }
        )

    # 分页器
    # 重写自定义get_paginated_response方法，实现自定义字段的排序
    def get_paginated_response(self, data):
        """
        request.query_params 中可以获取?param1=32&param2=23形式的参数.
        request.query_params 返回的数据类型为QueryDict
        """
        # 从查询字符串中获取到ordering参数
        ordering = self.request.query_params.get("ordering", "")
        reverse = False
        if ordering:
            # 降序
            if ordering.startswith("-"):
                reverse = True
                ordering = ordering[1:]
            # 列表排序
            data.sort(key=lambda item: item[ordering], reverse=reverse)

        return Response(
            {
                "code": 0,
                "data": {
                    "table_column": self.table_column,
                    "table_data": {
                        "total": self.paginator.count,
                        "data": data
                    }
                }
            }
        )

四、数据的创建

　　request.data获取form表单数据

class SurveysDetailApi(RetrieveAPIView, CreateAPIView):
    """
    RetrieveAPIView 获取一条数据
    CreateAPIView 创建数据
    """
    queryset = models.Survey.objects.all()
    # 实例化一个自定义的详情页序列化器
    serializer_class = basic.SurveyDetailSerializer

    # 请求调查表详情页
    def get_serializer_class(self):
        if self.request.method == "GET":
            # 序列化器读取操作
            return basic.SurveyDetailSerializer
        else:
            # 序列化器创建操作
            return basic.SurveyCreateSerializer

    # 字段校验，创建调查表
    # 重写CreateAPIView的方法
    def create(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)
        # 这里时serializer是通过序列化器实例化的对象，所有调用的serializers.ModelSerializer的is_valid方法
        if serializer.is_valid():
            # 同理：这里调用serializers.ModelSerializer的save方法
            data = serializer.save()
            return Response(
                {
                    "code": 0,
                    "data": data
                }
            )
        else:
            return Response(
                {
                    "code": 1,
                    "errors": serializer.errors
                }
            )