序列化组件
# 模型层
from django.db import models
class Book(models.Model):
nid = models.AutoField(primary_key=True)
name = models.CharField(max_length=32)
price = models.DecimalField(max_digits=5, decimal_places=2)
publish_date = models.DateField()
publish = models.ForeignKey(to='Publish', to_field='nid', on_delete=models.CASCADE)
authors = models.ManyToManyField(to='Author')
def __str__(self):
return self.name
class Author(models.Model):
nid = models.AutoField(primary_key=True)
name = models.CharField(max_length=32)
age = models.IntegerField()
author_detail = models.OneToOneField(to='AuthorDatail', to_field='nid', unique=True, on_delete=models.CASCADE)
class AuthorDatail(models.Model):
nid = models.AutoField(primary_key=True)
telephone = models.BigIntegerField()
birthday = models.DateField()
addr = models.CharField(max_length=64)
class Publish(models.Model):
nid = models.AutoField(primary_key=True)
name = models.CharField(max_length=32)
city = models.CharField(max_length=32)
email = models.EmailField()
def __str__(self):
return self.name
def test(self):
return self.email
一、利用for循环来实现序列化(繁琐)
def get(self, request):
response = {'status': 100, 'data': None}
ll = [{'name': book.name, 'price': book.price} for book in books]
# 返回数据是json格式数据
response['data'] = ll
# safe = True 表示数据可以是列表
return JsonResponse(response, safe=False)
二、利用Django提供的序列化组件(不可控需要的字段)
Django内置的serializers
from django.core import serializers
def get(self,request):
books = models.Book.objects.all()
ret=serializers.serialize('json','queryset对象')
#ret就是序列化之后的字符串了,不需要再序列化了
return HttpResponse(ret)
三、利用drf提供的序列化组件
1、基于Serializer类实现序列化——基本语法
-1 先导入
from rest_framework.serializers import Serializer
from rest_framework import serializers
-2 写一个类,继承Serializer
-3 在类内部写属性:
name=serializers.CharField()
-4 使用:
先生成对象,需要传参数 instance:要序列化的对象(可能是queryset,也可能是单个对象)
many:如果是queryset---True,,如果是单个对象--False
-5 序列化的数据:对象.data --->是一个字典
from rest_framework.views import APIView
from rest_framework import serializers
class BookSerializer(serializers.Serializer):
name = serializers.CharField()
class Book(APIView):
def get(self, request):
# 要序列化的对象(可以是queryset,也可以是单个对象)
# book = models.Books.objects.filter(name='红楼梦').first()
# ser = BookSerializer(instance=book,many=False)
books = models.Books.objects.all()
ser = BookSerializer(instance=books, many=True)
data = ser.data
return JsonResponse(data, safe=False)
2、基于Serializer类实现序列化——高级语法
(1)非关联字段或一对多字段
- 可以不用source,直接用 字段名 当变量名,必须为字段名
- 也可以用
source
来指定需要的目标字段 (推荐,尽量让字段名不要泄露) -
source
也可以用来指定模型层中的方法 - 一对多关联关系,可以在 source 中用
.
来指定字段,例如取出版社名字,用source='publish.name'
from rest_framework.views import APIView
from rest_framework import serializers
class BookSerializer(serializers.Serializer):
# 利用source来指定魔表字段,给key取别名
aaa = serializers.CharField(source='name') # 等价于 name = serializers.CharField()
price = serializer.CharField()
publish_name = serializer.CharField(source='publish.name')
# source 也可以用来指定模型层中的方法
t = serializer.CharField(source='publish.test')
class Book(APIView):
def get(self, request):
books = models.Books.objects.all()
ser = BookSerializer(instance=books, many=True)
data = ser.data
return JsonResponse(data, safe=False)
(2)一对多或者多对多字段
- 多对多要用
SerializerMethodField()
,然后定义一个get_变量名
的方法,方法名字必须为 get_变量名 -
get_变量名
方法要传参,传入当前对象,例如在 BookSerializer 中就是book对象 - 在
get_变量名
方法中,也可以对数据进行序列化,例如取书的所有作者,就可以对作者序列化然后 return
from rest_framework.views import APIView
from rest_framework import serializers
# 用于对author的数据进行序列化
class AuthorSerializer(serliazer.Serializer):
name = serializer.CharField()
age = serializer.CharField()
class BookSerializer(serializers.Serializer):
# 利用source来给key取别名
aaa = serializers.CharField(source='name') # 等价于 name = serializers.CharField()
price = serializer.CharField()
# book和publish是一对多的关系,也可以用SerializerMethodField
publish = serializer.SerializerMethodField()
def get_publish(self, book):
pub = book.publish.name
return pub
# book和authors是多对多的关系,用SerializerMethodField
au = serializer.SerializerMethodField()
def get_au(self, obj):
aus = obj.authors.all()
ll = []
for obj_au in aus:
ll.append({'au_name':obj_au.name,'au_age':obj_au.age})
return ll
# 也可以在方法中使用序列化类序列化
'''
def get_au(self, book):
# 获取这本书的所有作者
aus = book.authors.all()
# 可以在方法中对authors的数据进行序列化
au_ser = AuthorSerializer(aus,many=True)
return au_ser.data
'''
class Book(APIView):
def get(self, request):
books = models.Books.objects.all()
ser = BookSerializer(instance=books, many=True)
data = ser.data
return JsonResponse(data, safe=False)
3、基于ModelSerializer类实现序列化
(1)基本语法
from app01.models import Book
# 这样序列化得到的数据,authors是中都是author_id
class BookSerializer(serializer.ModelSerializer):
class Meta:
model = Book
fields = '__all__'
(2)重写属性
from app01.models import Book
# 这样序列化得到的数据,authors中都是author_id,publish也是publish_id
class BookSerializer(serializer.ModelSerializer):
class Meta:
model = Book
fields = '__all__'
# 重写属性authors和publish
puhlish = serializer.CharField(source='publish.name')
authors = serializers.SerializerMethodField()
def get_authors(self,book):
aus = book.authors.all()
# 可以在方法中对authors的数据进行序列化
au_ser = AuthorSerializer(aus,many=True)
return au_ser.data
(3)其他属性
- fields = ['id','name'] ---------> 指定序列化这两个字段
- exclude = ['publish','create_time'] ----------> 除了这两个字段外,其余的序列化
- depth = 2 ----------> 指定深度,即跨表。值为1表示跨一次表;值为2表示跨两次表
class BookSerializer(serializers.ModelSerializer):
# 必须写一个内部类,名字叫Meta
class Meta:
model = Book
# fields = '__all__'
# 指定只取这两个字段
fields = ['nid','name']
# 去掉指定的字段
# exclude=['publish','authors']
# fields,跟exclude不能连用
# 指定深度(官方建议小于10,我给你的建议小于3)
depth = 2
4、HyperlinkedIdentityField(带链接的序列化)-----很少用
# url层
url(r'book/$',views.Book.as_view()),
url(r'publish/(?P<pk>\d+)',views.Publish.as_view(),name='ttt')
# view层
# 定义一个序列化类
class BookSerializer(serializers.Serializers):
name = serializers.CharField()
# view_name:路由的名字;lookup_field:根据表的哪个字段;lookup_url_kwarg:反向解析有名分组的名字。------lookup_field与lookup_url_kwarg相当于是key与value
publish = serializers.HyperlinkedIdentityField(view_name='ttt', lookup_field='publish_id',lookup_url_kwarg='pk')
# 最后得到的链接是: http://127.0.0.1:8000/publish/1
# CBV
class Book(APIView):
def get(self, request):
books = models.Book.objects.all()
# 必须要传过去request,以便在链接中拼接域名
ser = BookSerializer(books, many=True, context={'request':request})
return JsonResponse(ser.data,safe=False)
5、序列化组件之请求数据校验和保存功能
-
序列化类必须继承
ModelSerializer
类,只有该类可以指定数据保存修改的目标表模型。倘若一定要继承Serializer
类,可以通过重写save方法,来实现保存和修改数据 -
序列化组件校验和forms组件类似
-
钩子函数抛异常,异常是 rest_framework.exceptions 下的 ValidationError
-
新增数据:
新增数据,将数据传入实例化类产生对象,通过is_valid()
校验,校验通过,利用序列化对象的save()
方法保存ser=BookSerializer(data=request.data) if ser.is_valid(): ser.save()
-
修改数据:
修改数据一定要在实例化序列化类的时候传参instance='要修改的对象'
指定要修改的对象ret = models.Book.objects.filter(name=request.data.get('name')).first() ser=BookSerializer(data=request.data, instance=ret') if ser.is_valid(): ser.save()
# 定义一个序列化类
from rest_framework.exceptions import ValidationError
class BookSerializer(serializerss.ModelSerializer):
class Meta:
model = Book
fields = '__all__'
# 校验和forms组件类似
name = serializers.CharField(max_length=10,required=True,error_message={'max_length':最长不能超过10位,'requered':'必须填'})
# 局部钩子,value是前端传过来的数据
def validate_name(self,value):
if value.startswith('aa'):
raise ValidationError('不能以aa开头')
return value
# 全局钩子 ,这里的value是上面验证通过后的所有数据构成的字典
def validate(self,value):
pwd = value.get('pwd')
re_pwd = value.get('re_pwd')
if pwd == re_pwd:
return value
raise ValidationError('两次密码不一致')
# CBV
# 1. 新增对象
class Book(APIView):
def post(self, request, *args, **kwargs):
response = {'status': 100, 'msg': None}
data = request.data
ser = BookSerializer(data=data)
if ser.is_valid():
ser.save()
response['msg'] = '创建成功'
else:
response['status'] = 101
response['msg'] = ser.errors
return JsonResponse(response, safe=False)
# CBV
# 2.修改数据
class Book(APIView):
def put(self, request, *args, **kwargs):
response = {'status': 100, 'msg': None}
data = request.data
ser = BookSerializer(data=data,instance=)
if ser.is_valid():
ser.save()
response['msg'] = '创建成功'
else:
response['status'] = 101
response['msg'] = ser.errors
return JsonResponse(response, safe=False)
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