如何使一个Python类序列化?

class FileItem:
    def __init__(self, fname):
        self.fname = fname

尝试序列化为JSON:

>>> import json
>>> x = FileItem('/foo/bar')
>>> json.dumps(x)
TypeError: Object of type 'FileItem' is not JSON serializable

当前回答

这对我来说很有效:

class JsonSerializable(object):

    def serialize(self):
        return json.dumps(self.__dict__)

    def __repr__(self):
        return self.serialize()

    @staticmethod
    def dumper(obj):
        if "serialize" in dir(obj):
            return obj.serialize()

        return obj.__dict__

然后

class FileItem(JsonSerializable):
    ...

and

log.debug(json.dumps(<my object>, default=JsonSerializable.dumper, indent=2))

其他回答

基于Quinten Cabo的回答:

def sterilize(obj):
    """Make an object more ameniable to dumping as json
    """
    if type(obj) in (str, float, int, bool, type(None)):
        return obj
    elif isinstance(obj, dict):
        return {k: sterilize(v) for k, v in obj.items()}
    list_ret = []
    dict_ret = {}
    for a in dir(obj):
        if a == '__iter__' and callable(obj.__iter__):
            list_ret.extend([sterilize(v) for v in obj])
        elif a == '__dict__':
            dict_ret.update({k: sterilize(v) for k, v in obj.__dict__.items() if k not in ['__module__', '__dict__', '__weakref__', '__doc__']})
        elif a not in ['__doc__', '__module__']:
            aval = getattr(obj, a)
            if type(aval) in (str, float, int, bool, type(None)):
                dict_ret[a] = aval
            elif a != '__class__' and a != '__objclass__' and isinstance(aval, type):
                dict_ret[a] = sterilize(aval)
    if len(list_ret) == 0:
        if len(dict_ret) == 0:
            return repr(obj)
        return dict_ret
    else:
        if len(dict_ret) == 0:
            return list_ret
    return (list_ret, dict_ret)

区别在于

Works for any iterable instead of just list and tuple (it works for NumPy arrays, etc.) Works for dynamic types (ones that contain a __dict__). Includes native types float and None so they don't get converted to string. Classes that have __dict__ and members will mostly work (if the __dict__ and member names collide, you will only get one - likely the member) Classes that are lists and have members will look like a tuple of the list and a dictionary Python3 (that isinstance() call may be the only thing that needs changing)

Json在它可以打印的对象方面受到限制,而jsonpickle(你可能需要一个PIP安装jsonpickle)在它不能缩进文本方面受到限制。如果你想检查一个你不能改变类的对象的内容,我仍然找不到比:

 import json
 import jsonpickle
 ...
 print  json.dumps(json.loads(jsonpickle.encode(object)), indent=2)

注意:他们仍然不能打印对象方法。

一个非常简单的一行程序解决方案

import json

json.dumps(your_object, default=lambda __o: __o.__dict__)

结束!

下面是一个测试。

import json
from dataclasses import dataclass


@dataclass
class Company:
    id: int
    name: str

@dataclass
class User:
    id: int
    name: str
    email: str
    company: Company


company = Company(id=1, name="Example Ltd")
user = User(id=1, name="John Doe", email="john@doe.net", company=company)


json.dumps(user, default=lambda __o: __o.__dict__)

输出:

{
  "id": 1, 
  "name": "John Doe", 
  "email": "john@doe.net", 
  "company": {
    "id": 1, 
    "name": "Example Ltd"
  }
}

Jsonweb似乎是我的最佳解决方案。参见http://www.jsonweb.info/en/latest/

from jsonweb.encode import to_object, dumper

@to_object()
class DataModel(object):
  def __init__(self, id, value):
   self.id = id
   self.value = value

>>> data = DataModel(5, "foo")
>>> dumper(data)
'{"__type__": "DataModel", "id": 5, "value": "foo"}'

Kyle Delaney的评论是正确的,所以我尝试使用https://stackoverflow.com/a/15538391/1497139以及https://stackoverflow.com/a/10254820/1497139的改进版本

创建一个“JSONAble”mixin。

因此,要使一个类JSON可序列化使用“JSONAble”作为超类,并调用:

 instance.toJSON()

or

 instance.asJSON()

对于这两种方法。您还可以使用本文提供的其他方法扩展JSONAble类。

家庭和个人单元测试样本的测试示例结果如下:

toJSOn ():

{
    "members": {
        "Flintstone,Fred": {
            "firstName": "Fred",
            "lastName": "Flintstone"
        },
        "Flintstone,Wilma": {
            "firstName": "Wilma",
            "lastName": "Flintstone"
        }
    },
    "name": "The Flintstones"
}

asJSOn ():

{'name': 'The Flintstones', 'members': {'Flintstone,Fred': {'firstName': 'Fred', 'lastName': 'Flintstone'}, 'Flintstone,Wilma': {'firstName': 'Wilma', 'lastName': 'Flintstone'}}}

使用家庭和个人样本进行单元测试

def testJsonAble(self):
        family=Family("The Flintstones")
        family.add(Person("Fred","Flintstone")) 
        family.add(Person("Wilma","Flintstone"))
        json1=family.toJSON()
        json2=family.asJSON()
        print(json1)
        print(json2)

class Family(JSONAble):
    def __init__(self,name):
        self.name=name
        self.members={}
    
    def add(self,person):
        self.members[person.lastName+","+person.firstName]=person

class Person(JSONAble):
    def __init__(self,firstName,lastName):
        self.firstName=firstName;
        self.lastName=lastName;

JSONAble .py定义JSONAble mixin

 '''
Created on 2020-09-03

@author: wf
'''
import json

class JSONAble(object):
    '''
    mixin to allow classes to be JSON serializable see
    https://stackoverflow.com/questions/3768895/how-to-make-a-class-json-serializable
    '''

    def __init__(self):
        '''
        Constructor
        '''
    
    def toJSON(self):
        return json.dumps(self, default=lambda o: o.__dict__, 
            sort_keys=True, indent=4)
        
    def getValue(self,v):
        if (hasattr(v, "asJSON")):
            return v.asJSON()
        elif type(v) is dict:
            return self.reprDict(v)
        elif type(v) is list:
            vlist=[]
            for vitem in v:
                vlist.append(self.getValue(vitem))
            return vlist
        else:   
            return v
    
    def reprDict(self,srcDict):
        '''
        get my dict elements
        '''
        d = dict()
        for a, v in srcDict.items():
            d[a]=self.getValue(v)
        return d
    
    def asJSON(self):
        '''
        recursively return my dict elements
        '''
        return self.reprDict(self.__dict__)   

您将发现这些方法现在集成在https://github.com/WolfgangFahl/pyLoDStorage项目中,该项目可在https://pypi.org/project/pylodstorage/上获得