序列化类外键字段的覆盖,十大接口序列化总结,视图家族

序列化类外键字段的覆盖

"""
1)在序列化类中自定义字段,名字与model类中属性名一致,就称之为覆盖操作
    (覆盖的是属性的所有规则:extra_kwargs中指定的简易规则、model字段提供的默认规则、数据库唯一约束等哪些规则)

2)外键覆盖字段用PrimaryKeyRelatedField来实现,可以做到只读、只写、可读可写三种形式
    只读:read_only=True
    只写:queryset=关联表的queryset, write_only=True
    可读可写:queryset=关联表的queryset
    
3)当外界关联的数据是多个时,需标识many=True条件
"""
class BookModelSerializer(serializers.ModelSerializer):
    # 如何覆盖外键字段
    # publish = serializers.PrimaryKeyRelatedField(read_only=True)  # 只读
    # publish = serializers.PrimaryKeyRelatedField(queryset=models.Publish.objects.all(), write_only=True)  # 只写
    # publish = serializers.PrimaryKeyRelatedField(queryset=models.Publish.objects.all())  # 可读可写

    publish = serializers.PrimaryKeyRelatedField(queryset=models.Publish.objects.all())
    authors = serializers.PrimaryKeyRelatedField(queryset=models.Author.objects.all(), many=True)

    class Meta:
        model = models.Book
        fields = ('name', 'price', 'image', 'publish', 'authors')

十大接口序列化总结

"""
def __init__(self, instance=None, data=empty, **kwargs):
    pass

instance:是要被赋值对象的 - 对象类型数据赋值给instance
data:是要被赋值数据的 - 请求来的数据赋值给data
kwargs:内部有三个属性:many、partial、context
    many:操作的对象或数据,是单个的还是多个的
    partial:在修改需求时使用,可以将所有校验字段required校验规则设置为False
    context:用于视图类和序列化类直接传参使用
"""

# 常见使用
# 单查接口
UserModelSerializer(instance=user_obj)

# 群查接口
UserModelSerializer(instance=user_query, many=True)

# 单增接口,request.data是字典
UserModelSerializer(data=request.data) 

# 群增接口,request.data是列表
UserModelSerializer(data=request.data, many=True)

# 单整体改接口,request.data是字典
UserModelSerializer(instance=user_obj, data=request.data)

# 群整体改接口,request.data是列表,且可以分离出pks,转换成user_queryset
UserModelSerializer(instance=user_queryset, data=request.data, many=True)

# 单局部改接口,request.data是字典
UserModelSerializer(instance=user_obj, data=request.data, partial=True)

# 群局部改接口,request.data是列表,且可以分离出pks,转换成user_queryset
UserModelSerializer(instance=user_queryset, data=request.data, partial=True, many=True)

# 删接口,用不到序列化类

十大接口核心知识小结

"""
1)初始化序列化类,设置partial=True可以将所有反序列化字段的 required 设置为 False(提供就校验,不提供不校验),可以运用在局部修改接口

2)初始化序列化类,设置context={...},在序列化类操作self.context,实现视图类和序列化类数据互通

3)只有要完成资源的群改这种特殊需求时,才需要自定义ListSerializer绑定给自定义的ModelSerializer,重写update方法,来完成需求
"""

案例

models.py
# 基类:是抽象的(不会完成数据库迁移),目的是提供共有字段的
class BaseModel(models.Model):
    is_delete = models.BooleanField(default=False)
    updated_time = models.DateTimeField(auto_now_add=True)

    class Meta:
        abstract = True  # 必须完成该配置

class Book(BaseModel):
    name = models.CharField(max_length=64)
    price = models.DecimalField(max_digits=5, decimal_places=2, null=True)
    image = models.ImageField(upload_to='img', default='img/default.png')

    publish = models.ForeignKey(to='Publish', related_name='books', db_constraint=False, on_delete=models.DO_NOTHING)
    authors = models.ManyToManyField(to='Author', related_name='books', db_constraint=False)
    
    @property  # @property字段默认就是read_only,且不允许修改
    def publish_name(self):
        return self.publish.name

    @property  # 自定义序列化过程
    def author_list(self):
        temp_author_list = []
        for author in self.authors.all():
            author_dic = {
                "name": author.name
            }
            try:
                author_dic['phone'] = author.detail.phone
            except:
                author_dic['phone'] = ''
            temp_author_list.append(author_dic)
        return temp_author_list
    

class Publish(BaseModel):
    name = models.CharField(max_length=64)


class Author(BaseModel):
    name = models.CharField(max_length=64)


class AuthorDetail(BaseModel):
    phone = models.CharField(max_length=11)
    author = models.OneToOneField(to=Author, related_name='detail', db_constraint=False, on_delete=models.CASCADE)
urls.py
url(r'^books/$', views.BookAPIView.as_view()),
url(r'^books/(?P<pk>\d+)/$', views.BookAPIView.as_view()),
serializers.py
from rest_framework import serializers
from . import models

# 群增群改辅助类(了解)
class BookListSerializer(serializers.ListSerializer):
    """
    1)create群增方法不需要重新
    2)update群改方法需要重写,且需要和views中处理request.data的逻辑配套使用
    3)self.child就代表该ListSerializer类绑定的ModelSerializer类
        BookListSerializer的self.child就是BookModelSerializer
    """
    # 重新update方法
    def update(self, queryset, validated_data_list):
        return [
            self.child.update(queryset[index], validated_data) for index, validated_data in enumerate(validated_data_list)
        ]

# 主序列化类
class BookModelSerializer(serializers.ModelSerializer):
    class Meta:
        # 配置自定义群增群改序列化类
        list_serializer_class = BookListSerializer

        model = models.Book
        fields = ('name', 'price', 'image', 'publish', 'authors', 'publish_name', 'author_list')
        # fields = ('name', 'price', 'image', 'publish', 'authors', 'abc')
        extra_kwargs = {
            'image': {
                'read_only': True,
            },
            'publish': {  # 系统原有的外键字段,要留给反序列化过程使用,序列化外键内容,用@property自定义
                'write_only': True,
            },
            'authors': {
                'write_only': True,
            },
        }

    # 需求:内外传参
    # 1)在钩子函数中,获得请求请求对象request 视图类 => 序列化类
    # 2)序列化钩子校验过程中,也会产生一些数据,这些数据能不能传递给外界使用:序列化类 => 视图类
    # 序列化类的context属性,被视图类与序列化类共享
    def validate(self, attrs):
        print(self.context)  # 可以获得视图类在初始化序列化对象时传入的context
        # self.context.update({'a': 10})  # 序列化类内部更新context,传递给视图类
        return attrs
views.py
from rest_framework.views import APIView
from . import models, serializers
from .response import APIResponse

# 六个必备接口:单查、群查、单增、单删、单整体改(了解)、单局部改
# 四个额外接口:群增、群删、群整体改、群局部改
class BookAPIView(APIView):
    # 单查群查
    """
    单查:接口:/books/(pk)/
    群查:接口:/books/
    """
    def get(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        if pk:
            obj = models.Book.objects.filter(is_delete=False, pk=pk).first()
            serializer = serializers.BookModelSerializer(instance=obj)
            return APIResponse(result=serializer.data)
        else:
            queryset = models.Book.objects.filter(is_delete=False).all()
            serializer = serializers.BookModelSerializer(instance=queryset, many=True)
            return APIResponse(results=serializer.data)

    # 单增群增
    """
    单增:接口:/books/   数据:dict
    群增:接口:/books/   数据:list
    """
    def post(self, request, *args, **kwargs):
        # 如何区别单增群增:request.data是{}还是[]
        if not isinstance(request.data, list):
            # 单增
            serializer = serializers.BookModelSerializer(data=request.data)
            serializer.is_valid(raise_exception=True)  # 如果校验失败,会直接抛异常,返回给前台
            obj = serializer.save()
            # 为什么要将新增的对象重新序列化给前台:序列化与反序列化数据不对等
            return APIResponse(result=serializers.BookModelSerializer(obj).data, http_status=201)
        else:
            # 群增
            serializer = serializers.BookModelSerializer(data=request.data, many=True)
            serializer.is_valid(raise_exception=True)  # 如果校验失败,会直接抛异常,返回给前台
            objs = serializer.save()
            # 为什么要将新增的对象重新序列化给前台:序列化与反序列化数据不对等
            return APIResponse(result=serializers.BookModelSerializer(objs, many=True).data, http_status=201)

    # 单删群删
    """
    单删:接口:/books/(pk)/
    群删:接口:/books/   数据:[pk1, ..., pkn]
    """
    def delete(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        if pk:
            pks = [pk]  # 将单删伪装成群删一条
        else:
            pks = request.data  # 群删的数据就是群删的主键们

        try:  # request.data可能提交的是乱七八糟的数据,所以orm操作可能会异常
            rows = models.Book.objects.filter(is_delete=False, pk__in=pks).update(is_delete=True)
        except:
            return APIResponse(1, '数据有误')

        if rows:  # 只要有受影响的行,就代表删除成功
            return APIResponse(0, '删除成功')

        return APIResponse(2, '删除失败')

    # 单整体改群整体改
    """
    单整体改:接口:/books/(pk)/ 数据:dict
    群整体改:接口:/books/   数据:[{pk1, ...}, ..., {pkn, ...}] | {pks: [pk1, ..., pkn], data: [{}, ..., {}]}
    """
    def put(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        if pk:  # 单
            try:
                instance = models.Book.objects.get(is_delete=False, pk=pk)
            except:
                return APIResponse(1, 'pk error', http_status=400)
            # 序列化类同时赋值instance和data,代表用data重新更新instance => 修改
            serializer = serializers.BookModelSerializer(instance=instance, data=request.data)
            serializer.is_valid(raise_exception=True)
            obj = serializer.save()
            return APIResponse(result=serializers.BookModelSerializer(obj).data)
        else:  # 群
            """ 分析request.data数据 [{'pk':1, 'name': '', 'publish': 1, 'authors': [1, 2]}, ...]
            1)从 request.data 中分离出 pks 列表
            2)pks中存放的pk在数据库中没有对应数据,或者对应的数据已经被删除了,这些不合理的pk要被剔除
            3)pks最终转换得到的 objs 列表长度与 request.data 列表长度不一致,就是数据有误
            """
            pks = []
            try:  # 只要不是要求的标准数据,一定会在下方四行代码某一行抛出异常
                for dic in request.data:
                    pks.append(dic.pop('pk'))
                objs = models.Book.objects.filter(is_delete=False, pk__in=pks)
                assert len(objs) == len(request.data)  # 两个列表长度必须一致
            except:
                return APIResponse(1, '数据有误', http_status=400)

            serializer = serializers.BookModelSerializer(instance=objs, data=request.data, many=True)
            serializer.is_valid(raise_exception=True)
            objs = serializer.save()
            return APIResponse(result=serializers.BookModelSerializer(objs, many=True).data)


    # 单局部改群局部改
    """
    单局部改:接口:/books/(pk)/ 数据:dict
    群局部改:接口:/books/   数据:[{pk1, ...}, ..., {pkn, ...}] | {pks: [pk1, ..., pkn], data: [{}, ..., {}]}
    """
    def patch(self, request, *args, **kwargs):
        pk = kwargs.get('pk')
        if pk:  # 单
            try:
                instance = models.Book.objects.get(is_delete=False, pk=pk)
            except:
                return APIResponse(1, 'pk error', http_status=400)
            # partial=True就是将所有反序列化字段的 required 设置为 False(提供就校验,不提供不校验)
            serializer = serializers.BookModelSerializer(instance=instance, data=request.data, partial=True)
            serializer.is_valid(raise_exception=True)
            obj = serializer.save()
            return APIResponse(result=serializers.BookModelSerializer(obj).data)
        else:  # 群
            pks = []
            try:  # 只要不是要求的标准数据,一定会在下方三行代码某一行抛出异常
                for dic in request.data:
                    pks.append(dic.get('pk'))
                objs = models.Book.objects.filter(is_delete=False, pk__in=pks)
                assert len(objs) == len(request.data)  # 两个列表长度必须一致
            except:
                return APIResponse(1, '数据有误', http_status=400)

            serializer = serializers.BookModelSerializer(
                instance=objs,
                data=request.data,
                many=True,
                partial=True,
                context={'request': request}  # 初始化时,对context赋值,将视图类中数据传递给序列化类
            )

            serializer.is_valid(raise_exception=True)
            objs = serializer.save()

            print(serializer.context)  # 在完成序列化类校验后,可以重新拿到序列化类内部对context做的值更新
            return APIResponse(result=serializers.BookModelSerializer(objs, many=True).data)

视图家族

"""
视图基类:APIView、GenericAPIView
视图工具类:mixins包下的五个类(六个方法)
工具视图类:generics包下的所有GenericAPIView的子类
视图集:viewsets包下的类
"""

""" GenericAPIView基类(基本不会单独使用,了解即可,但是是高级视图类的依赖基础)
1)GenericAPIView继承APIView,所有APIView子类写法在继承GenericAPIView时可以保持一致
2)GenericAPIView给我们提供了三个属性 queryset、serializer_class、lookup_field
3)GenericAPIView给我们提供了三个方法 get_queryset、get_serializer、get_obj
"""


""" mixins包存放了视图工具类(不能单独使用,必须配合GenericAPIView使用)
CreateModelMixin:单增工具类
    create方法
    
ListModelMixin:群查工具类
    list方法

RetrieveModelMixin:单查工具类
    retrieve方法

UpdateModelMixin:单整体局部改工具类
    update方法

DestroyModelMixin:单删工具类
    destory方法
"""

""" generics包下的所有GenericAPIView的子类(就是继承GenericAPIView和不同mixins下的工具类的组合)
1)定义的视图类,继承generics包下已有的特点的GenericAPIView子类,可以在只初始化queryset和serializer_class两个类属性后,就获得特定的功能

2)定义的视图类,自己手动继承GenericAPIView基类,再任意组合mixins包下的一个或多个工具类,可以实现自定义的工具视图类,获得特定的功能或功能们

注:
i)在这些模式下,不能实现单查群查共存(可以加逻辑区分,也可以用视图集知识)
ii)DestroyModelMixin工具类提供的destory方法默认是从数据库中删除数据,所以一般删除数据的需求需要自定义逻辑
"""
urls.py
from django.conf.urls import url
from . import views

urlpatterns = [
    # ...
    
    url(r'^v1/books/$', views.BookV1APIView.as_view()),
    url(r'^v1/books/(?P<pk>\d+)/$', views.BookV1APIView.as_view()),

    url(r'^v2/books/$', views.BookV2APIView.as_view()),
    url(r'^v2/books/(?P<pk>\d+)/$', views.BookV2APIView.as_view()),

    url(r'^v3/books/$', views.BookV3APIView.as_view()),
    url(r'^v3/books/(?P<pk>\d+)/$', views.BookV3APIView.as_view()),
]
views.py
# ----------------------------- 过渡写法:了解 -----------------------------

from rest_framework.generics import GenericAPIView
class BookV1APIView(GenericAPIView):
    # 将数据和序列化提示为类属性,所有的请求方法都可以复用
    queryset = models.Book.objects.filter(is_delete=False).all()
    serializer_class = serializers.BookModelSerializer
    lookup_field = 'pk'  # 可以省略,默认是pk,与url有名分组对应的

    # 群查
    def get(self, request, *args, **kwargs):
        # queryset = models.Book.objects.filter(is_delete=False).all()  # => 方法+属性两行代码
        queryset = self.get_queryset()
        # serializer = serializers.BookModelSerializer(instance=queryset, many=True)  # => 方法+属性两行代码
        serializer = self.get_serializer(instance=queryset, many=True)
        return APIResponse(results=serializer.data)

    # 单查
    # def get(self, request, *args, **kwargs):
    #     obj = self.get_object()
    #     serializer = self.get_serializer(obj)
    #     return APIResponse(results=serializer.data)

    # 单增
    def post(self, request, *args, **kwargs):
        # serializer = serializers.BookModelSerializer(data=request.data)
        serializer = self.get_serializer(data=request.data)  # 同样的步骤多了,好处就来了
        serializer.is_valid(raise_exception=True)
        obj = serializer.save()
        return APIResponse(result=self.get_serializer(obj).data, http_status=201)
    
# ----------------------------- 过渡写法:了解 -----------------------------

from rest_framework.generics import GenericAPIView
from rest_framework import mixins
class BookV2APIView(GenericAPIView, mixins.RetrieveModelMixin, mixins.CreateModelMixin):
    queryset = models.Book.objects.filter(is_delete=False).all()
    serializer_class = serializers.BookModelSerializer

    # 单查
    def get(self, request, *args, **kwargs):
        # obj = self.get_object()
        # serializer = self.get_serializer(obj)
        # return APIResponse(results=serializer.data)

        # return self.retrieve(request, *args, **kwargs)

        response = self.retrieve(request, *args, **kwargs)
        return APIResponse(result=response.data)

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


# ----------------------------- 开发写法:常用 -----------------------------

from rest_framework.generics import RetrieveAPIView
class BookV3APIView(RetrieveAPIView):
    queryset = models.Book.objects.filter(is_delete=False).all()
    serializer_class = serializers.BookModelSerializer

    # 单查
    pass

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