序列化类外键字段的覆盖
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)
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
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
""" 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) # 单删群删接口,用不到序列化类
十大接口核心知识总结
- 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
- 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
- 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()),
serizlizers.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)