Django框架(十九)—— 序列化元件(serializer)
阿新 • • 發佈:2018-12-11
目錄
序列化元件
# 模型層 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迴圈來實現序列化(繁瑣)
def get(self, request):
response = {'status': 100, 'data': None}
ll = [{'name': book.name, 'price': book.price} for book in books]
# 返回資料是json格式資料
response['data'] = ll
# safe = True 表示資料可以是列表
return JsonResponse(response, safe=False)
二、利用Django提供的序列化元件(不可控需要的欄位)
Django內建的serializers
from django.core import serializers
def get(self,request):
books = models.Book.objects.all()
ret=serializers.serialize('json','queryset物件')
#ret就是序列化之後的字串了,不需要再序列化了
return HttpResponse(ret)
三、利用drf提供的序列化元件
1、基於Serializer類實現序列化——基本語法
-1 先匯入 from rest_framework.serializers import Serializer from rest_framework import serializers -2 寫一個類,繼承Serializer -3 在類內部寫屬性: name=serializers.CharField() -4 使用: 先生成物件,需要傳引數 instance:要序列化的物件(可能是queryset,也可能是單個物件) many:如果是queryset---True,,如果是單個物件--False -5 序列化的資料:物件.data --->是一個字典
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):
# 要序列化的物件(可以是queryset,也可以是單個物件)
# book = models.Books.objects.filter(name='紅樓夢').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、基於Serializer類實現序列化——高階語法
(1)非關聯欄位或一對多欄位
- 可以不用source,直接用 欄位名 當變數名,必須為欄位名
- 也可以用
source
來指定需要的目標欄位 (推薦,儘量讓欄位名不要洩露) source
也可以用來指定模型層中的方法- 一對多關聯關係,可以在 source 中用
.
來指定欄位,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來指定魔錶欄位,給key取別名
aaa = serializers.CharField(source='name') # 等價於 name = serializers.CharField()
price = serializer.CharField()
publish_name = serializer.CharField(source='publish.name')
# source 也可以用來指定模型層中的方法
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)一對多或者多對多欄位
- 多對多要用
SerializerMethodField()
,然後定義一個get_變數名
的方法,方法名字必須為 get_變數名 get_變數名
方法要傳參,傳入當前物件,例如在 BookSerializer 中就是book物件- 在
get_變數名
方法中,也可以對資料進行序列化,例如取書的所有作者,就可以對作者序列化然後 return
from rest_framework.views import APIView
from rest_framework import serializers
# 用於對author的資料進行序列化
class AuthorSerializer(serliazer.Serializer):
name = serializer.CharField()
age = serializer.CharField()
class BookSerializer(serializers.Serializer):
# 利用source來給key取別名
aaa = serializers.CharField(source='name') # 等價於 name = serializers.CharField()
price = serializer.CharField()
# book和publish是一對多的關係,也可以用SerializerMethodField
publish = serializer.SerializerMethodField()
def get_publish(self, book):
pub = book.publish.name
return pub
# book和authors是多對多的關係,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類序列化
'''
def get_au(self, book):
# 獲取這本書的所有作者
aus = book.authors.all()
# 可以在方法中對authors的資料進行序列化
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、基於ModelSerializer類實現序列化
(1)基本語法
from app01.models import Book
# 這樣序列化得到的資料,authors是中都是author_id
class BookSerializer(serializer.ModelSerializer):
class Meta:
model = Book
fields = '__all__'
(2)重寫屬性
from app01.models import Book
# 這樣序列化得到的資料,authors中都是author_id,publish也是publish_id
class BookSerializer(serializer.ModelSerializer):
class Meta:
model = Book
fields = '__all__'
# 重寫屬性authors和publish
puhlish = serializer.CharField(source='publish.name')
authors = serializer.SerializerMethodField()
def get_authors(self,book):
aus = book.authors.all()
# 可以在方法中對authors的資料進行序列化
au_ser = AuthorSerializer(aus,many=True)
return au_ser.data
(3)其他屬性
- fields = ['id','name'] ---------> 指定序列化這兩個欄位
- exclude = ['publish','create_time'] ----------> 除了這兩個欄位外,其餘的序列化
- depth = 2 ----------> 指定深度,即跨表。值為1表示跨一次表;值為2表示跨兩次表
class BookSerializer(serializers.ModelSerializer):
# 必須寫一個內部類,名字叫Meta
class Meta:
model = Book
# fields = '__all__'
# 指定只取這兩個欄位
fields = ['nid','name']
# 去掉指定的欄位
# exclude=['publish','authors']
# fields,跟exclude不能連用
# 指定深度(官方建議小於10,我給你的建議小於3)
depth = 2