我想将JSON数据转换为Python对象。

我从Facebook API收到JSON数据对象,我想将其存储在数据库中。

我的当前视图在Django (Python)(请求。POST包含JSON):

response = request.POST
user = FbApiUser(user_id = response['id'])
user.name = response['name']
user.username = response['username']
user.save()

这很好,但是如何处理复杂的JSON数据对象呢? 如果我能以某种方式将这个JSON对象转换为易于使用的Python对象,是不是会更好?


当前回答

你可以试试这个:

class User(object):
    def __init__(self, name, username):
        self.name = name
        self.username = username

import json
j = json.loads(your_json)
u = User(**j)

只需创建一个新对象,并将参数作为映射传递。


你也可以有一个带有对象的JSON:

import json
class Address(object):
    def __init__(self, street, number):
        self.street = street
        self.number = number

    def __str__(self):
        return "{0} {1}".format(self.street, self.number)

class User(object):
    def __init__(self, name, address):
        self.name = name
        self.address = Address(**address)

    def __str__(self):
        return "{0} ,{1}".format(self.name, self.address)

if __name__ == '__main__':
    js = '''{"name":"Cristian", "address":{"street":"Sesame","number":122}}'''
    j = json.loads(js)
    print(j)
    u = User(**j)
    print(u)

其他回答

更新

在Python3中,你可以使用SimpleNamespace和object_hook在一行中完成:

import json
from types import SimpleNamespace

data = '{"name": "John Smith", "hometown": {"name": "New York", "id": 123}}'

# Parse JSON into an object with attributes corresponding to dict keys.
x = json.loads(data, object_hook=lambda d: SimpleNamespace(**d))
print(x.name, x.hometown.name, x.hometown.id)

旧答案(Python2)

在Python2中,你可以使用namedtuple和object_hook在一行中完成(但对于嵌套对象非常慢):

import json
from collections import namedtuple

data = '{"name": "John Smith", "hometown": {"name": "New York", "id": 123}}'

# Parse JSON into an object with attributes corresponding to dict keys.
x = json.loads(data, object_hook=lambda d: namedtuple('X', d.keys())(*d.values()))
print x.name, x.hometown.name, x.hometown.id

或者,为了便于重用:

def _json_object_hook(d): return namedtuple('X', d.keys())(*d.values())
def json2obj(data): return json.loads(data, object_hook=_json_object_hook)

x = json2obj(data)

如果希望它处理不是很好的属性名称的键,请检查namedtuple的rename参数。

数据类向导是一种现代的选项,可以类似地为您工作。它支持自动键大小写转换,如camelCase或TitleCase,这两者在API响应中都很常见。

当将实例转储到dict/JSON时,默认的键转换是camelCase,但这可以很容易地使用主数据类上提供的Meta配置来覆盖。

https://pypi.org/project/dataclass-wizard/

from dataclasses import dataclass

from dataclass_wizard import fromdict, asdict


@dataclass
class User:
    name: str
    age: int
    is_active: bool


data = {
    'name': 'John',
    'age': 30,
    'isActive': True,
}

user = fromdict(User, data)
assert user == User(name='John', age=30, is_active=True)

json_dict = asdict(user)
assert json_dict == {'name': 'John', 'age': 30, 'isActive': True}

设置元配置的例子,当序列化为dict/JSON时,将字段转换为lisp-case:

DumpMeta(key_transform='LISP').bind_to(User)

我已经编写了一个名为any2any的小型(反)序列化框架,它可以帮助在两种Python类型之间进行复杂的转换。

在您的情况下,我猜您想从字典(通过json.loads获得)转换为复杂的对象response.education;Response.name,具有嵌套结构response.education.id,等等… 这就是这个框架的用途。文档还不是很好,但是通过使用any2any.simple。MappingToObject,你应该可以很容易地做到。如果需要帮助,请询问。

在寻找解决方案时,我偶然发现了这个博客:https://blog.mosthege.net/2016/11/12/json-deserialization-of-nested-objects/

它使用与前面回答中相同的技术,但使用了装饰器。 我发现另一件有用的事情是,它在反序列化结束时返回一个类型化对象

class JsonConvert(object):
    class_mappings = {}

    @classmethod
    def class_mapper(cls, d):
        for keys, cls in clsself.mappings.items():
            if keys.issuperset(d.keys()):   # are all required arguments present?
                return cls(**d)
        else:
            # Raise exception instead of silently returning None
            raise ValueError('Unable to find a matching class for object: {!s}'.format(d))

    @classmethod
    def complex_handler(cls, Obj):
        if hasattr(Obj, '__dict__'):
            return Obj.__dict__
        else:
            raise TypeError('Object of type %s with value of %s is not JSON serializable' % (type(Obj), repr(Obj)))

    @classmethod
    def register(cls, claz):
        clsself.mappings[frozenset(tuple([attr for attr,val in cls().__dict__.items()]))] = cls
        return cls

    @classmethod
    def to_json(cls, obj):
        return json.dumps(obj.__dict__, default=cls.complex_handler, indent=4)

    @classmethod
    def from_json(cls, json_str):
        return json.loads(json_str, object_hook=cls.class_mapper)

用法:

@JsonConvert.register
class Employee(object):
    def __init__(self, Name:int=None, Age:int=None):
        self.Name = Name
        self.Age = Age
        return

@JsonConvert.register
class Company(object):
    def __init__(self, Name:str="", Employees:[Employee]=None):
        self.Name = Name
        self.Employees = [] if Employees is None else Employees
        return

company = Company("Contonso")
company.Employees.append(Employee("Werner", 38))
company.Employees.append(Employee("Mary"))

as_json = JsonConvert.to_json(company)
from_json = JsonConvert.from_json(as_json)
as_json_from_json = JsonConvert.to_json(from_json)

assert(as_json_from_json == as_json)

print(as_json_from_json)

我正在寻找一个与recordclass一起工作的解决方案。RecordClass,支持嵌套对象,可用于json序列化和json反序列化。

扩展DS的答案,扩展BeneStr的解决方案,我想出了以下似乎有效的方法:

代码:

import json
import recordclass

class NestedRec(recordclass.RecordClass):
    a : int = 0
    b : int = 0

class ExampleRec(recordclass.RecordClass):
    x : int       = None
    y : int       = None
    nested : NestedRec = NestedRec()

class JsonSerializer:
    @staticmethod
    def dumps(obj, ensure_ascii=True, indent=None, sort_keys=False):
        return json.dumps(obj, default=JsonSerializer.__obj_to_dict, ensure_ascii=ensure_ascii, indent=indent, sort_keys=sort_keys)

    @staticmethod
    def loads(s, klass):
        return JsonSerializer.__dict_to_obj(klass, json.loads(s))

    @staticmethod
    def __obj_to_dict(obj):
        if hasattr(obj, "_asdict"):
            return obj._asdict()
        else:
            return json.JSONEncoder().default(obj)

    @staticmethod
    def __dict_to_obj(klass, s_dict):
        kwargs = {
            key : JsonSerializer.__dict_to_obj(cls, s_dict[key]) if hasattr(cls,'_asdict') else s_dict[key] \
                for key,cls in klass.__annotations__.items() \
                    if s_dict is not None and key in s_dict
        }
        return klass(**kwargs)

用法:

example_0 = ExampleRec(x = 10, y = 20, nested = NestedRec( a = 30, b = 40 ) )

#Serialize to JSON

json_str = JsonSerializer.dumps(example_0)
print(json_str)
#{
#  "x": 10,
#  "y": 20,
#  "nested": {
#    "a": 30,
#    "b": 40
#  }
#}

# Deserialize from JSON
example_1 = JsonSerializer.loads(json_str, ExampleRec)
example_1.x += 1
example_1.y += 1
example_1.nested.a += 1
example_1.nested.b += 1

json_str = JsonSerializer.dumps(example_1)
print(json_str)
#{
#  "x": 11,
#  "y": 21,
#  "nested": {
#    "a": 31,
#    "b": 41
#  }
#}