Django的序列化方法
.values 序列化结果
class BooksView(View):
def get(self, request):
book_list = Book.objects.values('id', 'title', 'chapter', 'pub_time', 'publisher')
book_list = list(book_list)
# 如果我们需要取外键关联的字段信息,需要循环获取外键,再去数据库查然后拼接成我们想要的
ret = []
for book in book_list:
pub_dict = {}
pub_obj = Publish.objects.filter(pk=book['publisher']).first()
pub_dict['id'] = pub_obj.pk
pub_dict['title'] = pub_obj.title
book['publisher'] = pub_dict
ret.append(book)
ret = json.dumps(book_list, ensure_ascii=False, cls=MyJson)
# json不能解决时间格式的数据
return HttpResponse(ret) # json.JSONEncoder.default()
# 解决json不能序列化时间字段的问题
class MyJson(json.JSONEncoder):
def default(self, field):
if isinstance(field, datetime.datetime):
return field.strftime('%Y-%m-%d %H:%M:%S')
elif isinstance(field, datetime.date):
return field.strftime('%Y-%m-%d')
else:
return json.JSONEncoder.default(self, field)
django serializers
from django.core import serializers # 能够得到我们要的效果,结构有点复杂
class BooksView(View):
def get(self, request):
book_list = Book.objects.all()
ret = serializers.serialize('json', book_list)
return HttpResponse(ret)
DRF序列化的方法
首先,我们要用DRF的序列化,就要遵循人家框架的一些标准,
-- Django我们CBV继承类是View,现在DRF我们要用APIView
-- Django中返回的时候我们用HTTPResponse,JsonResponse,render,DRF我们用Response
序列化
第一步,声明序列化类
// 定义一个序列化器类
class BookSerializer(serializers.Serializer):
id = serializers.IntegerField()
title = serializers.CharField(max_length=32)
CHOICES = ((1, 'Linux'),(2,'Django'),(3,'Python'))
chapter = serializers.ChoiceField(choices=CHOICES,
source='get_chapter_display')
pub_time = serializers.DateField()
第二步,序列化对象
from rest_framework.views import APIView
from rest_framework.response import Response class BookView(APIView):
def get(self, request):
book_list = Book.objects.all()
# 序列化对象,many=True为可以序列化多个
ret = BookSerializer(book_list, many=True)
# 序列化的数据存放在data中
return Response(ret.data)
外键关系的序列化
外键关系的序列化
from rest_framework import serializers
from .models import Book
class PublisherSerializer(serializers.Serializer):
id = serializers.IntegerField(read_only=True)
title = serializers.CharField(max_length=32) class UserSerializer(serializers.Serializer):
id = serializers.IntegerField(read_only=True)
name = serializers.CharField(max_length=32)
age = serializers.IntegerField() class BookSerializer(serializers.Serializer):
id = serializers.IntegerField(read_only=True)
title = serializers.CharField(max_length=32)
CHOICES = ((1,'Linux'),(2,'Python'),(3,'Go'))
category= serializers.ChoiceField(choices=CHOICES,
source='get_category_display',read_only=True)
pub_time = serializers.DateField() publisher = PublisherSerializer(read_only=True)
user = UserSerializer(many=True,read_only=True)
反序列化
当前端给我们发post的请求的时候~前端给我们传过来的数据~我们要进行一些校验然后保存到数据库~
首先~我们要写反序列化用的一些字段~有些字段要跟序列化区分开~~
Serializer提供了.is_vaild()和.save()方法~~
反序列化serializer.py
class BookSerializer(serializers.Serializer):
id = serializers.IntegerField(read_only=True)
title = serializers.CharField(max_length=32)
CHOICES = ((1,'Linux'),(2,'Python'),(3,'Go'))
category = serializers.ChoiceField(choices=CHOICES,
source='get_category_display',read_only=True)
post_category = serializers.IntegerField(write_only=True)
pub_time = serializers.DateField()
publisher = PublisherSerializer(read_only=True)
user = UserSerializer(many=True, read_only=True) users = serializers.ListField(write_only=True)
publisher_id = serializers.IntegerField(write_only=True) def create(self, validated_date):
book = Book.objects.create(title=validated_data['title'],
category=validated_data['post_category'], pub_time=validate_data['pub_time'],
publisher_id=validated_data['publisher_id'])
book.user.add(*validated_data['users'])
return book
反序列化views.py
class BookView(APIView):
def get(self, request):
book_list = Book.objects.all()
ret = BookSerializer(book_lilst, many=True)
return Response(ret.data) def post(self, request):
serializer = BookSerializer(data=request.data)
if serializer.is_valid():
serializer.save()
return Response(serializer.validated_data)
else:
return Response(serializer.errors)
当前端给我们发送patch请求的时候,前端传给我们用户要更新的数据,我们要对数据进行部分验证
PATCH请求Serializers.py
class BookSerializer(serializers.Serializer):
id = serializers.IntegerField(read_only=True)
title = serializers.CharField(max_length=32)
CHOICES = ((1,'Linux'),(2,'Python'),(3,'Go'))
category = serializers.ChoiceField(choices=CHOICES,
source='get_category_display',read_only=True)
post_category = serializers.IntegerField(write_only=True)
pub_time = serializers.DateField()
publisher = PublisherSerializer(read_only=True)
user = UserSerializer(many=True, read_only=True) users = serializers.ListField(write_only=True)
publisher_id = serializers.IntegerField(write_only=True) def create(self, validated_date):
book = Book.objects.create(title=validated_data['title'],
category=validated_data['post_category'], pub_time=validate_data['pub_time'],
publisher_id=validated_data['publisher_id'])
book.user.add(*validated_data['users'])
return book
def update(self, instance, validated_data):
instance.title = validated_data.get('title',instance.title)
instance.pub_time = validated_data.get("pub_time", instance.pub_time)
instance.category = validated_data.get("post_category", instance.category)
instance.publisher_id = validated_data.get("publisher_id", instance.publisher_id)
if validated_data.get("author_list"):
instance.authors.set(validated_data["author_list"])
instance.save()
return instance
put请求views.py
# 更新函数
class BookEditView(APIView):
def put(self, request, id):
book_obj = Book.objects.filter(id=id).first()
ser_obj = BookSerializer(instance=book_obj, data=request.data, partial=True)
if ser_obj.is_valid():
ser_obj.save()
return Response(ser_obj.validated_data)
return Response(ser_obj.errors)
验证--钩子函数
自定义验证钩子函数
# validators验证器
def my_validate(value):
print(1111)
if "敏感信息" in value.lower():
raise serializers.ValidationError("有敏感词汇")
return value
单个字段的钩子函数
class BookSerializer(serializers.Serializer):
id = serializers.IntegerField(required=False)
# 自定义钩子函数的使用
title = serializers.CharField(max_length=32, validators=[my_validate,]) # 单个验证函数,title这个字段必须在要序列化的字段中
# validate_字段名
def validate_title(self, value):
# value就是title的值 对value处理
if "python" not in value.lower():
raise serializers.ValidationError("标题必须含有python")
return value
多个字段的验证
def validate(self, attrs):
# attrs 是你传过来的所有的字段信息组成的字典
if "python" in attrs["title"].lower() or attrs["post_category"] == 1:
return attrs
else:
raise serializers.ValidationError("分类或标题不合符要求")
权重关系:
自定义验证 > 单个字段的验证 > 多个字段的验证
ModelSerializer
它会根据模型自动生成一组字段
它简单的默认实现了.update()以及.create()方法
定义一个ModelSerializer序列化
class BookSerializer(serializers.ModelSerializer):
class Meta:
model = Book
fields = "__all__"
# exclude=["id"]
# 会让你这些所有的外键关系变成read_only = True
# depth 代表找嵌套关系的第几层,
# depth = 1 # 外键关系的序列化
# 可以实现字段的不展现
extra_kwargs = {"publisher": {"write_only": True}, "authors":
{"write_only": True}}
SerializerMethodField
外键关联的对象有很多字段我们是用不到的~都传给前端会有数据冗余~就需要我们自己去定制序列化外键对象的哪些字段~~
class BookSerializer(serializers.ModelSerializer):
# SerializerMethodField方法调用get_authors_info这个方法并把返回值传给publisher_info
# 并在页面上展现出来
pu publisher_info = serializers.SerializerMethodField(read_only=True)
authors_info = serializers.SerializerMethodField(read_only=True) def get_authors_info(self, obj):
# obj 就是序列化的每个Book对象
authors_querset = obj.authors.all()
return [{"id": author.id, "name": author.name} for author in authors_querset] def get_publisher_info(self, obj):
publisher_obj = obj.publisher
return {"id": publisher_obj.id, "title": publisher_obj.title} class Meta:
model = Book
fields = "__all__"
# exclude=["id"]
# 会让你这些所有的外键关系变成read_only = True
# depth = 1
# 可以让一些字段不在页面上展现出来
extra_kwargs = {"publisher": {"write_only": True}, "authors":{"write_only": True}}
POST请求:重写了create方法
PUT/PATCH请求:重写update方法
save() 方法其实是调用了create方法