Django框架(十八)—— drf:序列化组件(serializer)

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
  • 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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转载自www.cnblogs.com/zhangbingsheng/p/10720746.html
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