Django 再谈一谈json序列化

from .models import UserInfo

def index(request):
  user_list = UserInfo.objects.all()
  import json
  return HttpResponse(json.dumps(user_list))
  # TypeError: Object of type 'QuerySet' is not JSON serializable

def index(request):
  user_list = UserInfo.objects.all()
  from django.core import serializers
  user_list_json = serializers.serialize("json", user_list)
  return HttpResponse(user_list_json)

[
 {
  "model": "app01.userinfo",
  "pk": 1,  
  "fields": {
    "name": "egon",
    "pwd": "123"
  }
},
{
  "model": "app01.userinfo",
  "pk": 2,
  "fields": {
    "name": "sb",
    "pwd": "123"
  }
}
]

import json
from datetime import date
from datetime import datetime

class JsonCustomEncoder(json.JSONEncoder):

  def default(self, field):

    if isinstance(field, datetime):
      return field.strftime('%Y-%m-%d %H:%M:%S')
    elif isinstance(field, date):
      return field.strftime('%Y-%m-%d')
    else:
      return json.JSONEncoder.default(self, field)

def index(request):
  now = datetime.now()
  import json
  return HttpResponse(json.dumps(now, cls=JsonCustomEncoder))

#django ORM的 Queryset对象默认无法被直接json.dumps()序列化，django.core提供的serializers模块提供将其序列化成str类型
#的功能，serializers处理后，再次json.dumps传给前端，前端需要经过两次json.Parse()处理，才能得到原对象类型，但是格式发
#生了变化，需要按新的方式取索引.例如：obj['pk']取主键，obj['fields']["caption"]取obj的caption字段
由QuerySet:[<Business: Business object>]
变为了：
[{"model": "cmdb.business", "pk": 1, "fields": {"caption": "develop"}}]

import json as default_json
from json.encoder import JSONEncoder


class BaseResponse(object):
  def __init__(self):
    self.status = True
    self.message = None
    self.data = None
    self.error = None
o=BaseResponse()

class JsonCustomEncoder(JSONEncoder):
  def default(self, o):
    if isinstance(o, BaseResponse):
      return o.__dict__
    return JSONEncoder.default(self, o)

o1=json.dumps(o,cls=JsonCustomEncoder)


> print(o1)
{"message": null, "error": null, "data": null, "status": true}
> print(type(o1))
<class 'str'>
#在序列化时指定cls参数，cls=自定义的序列化类，在自定义序列化类的default方法中判断，如果是指定的类的实例的话，则将该类转换成dict格式返回，若指定类的实例，则使用json模块默认的序列化方法。最终得到的return值为str类型。