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Python对象转换为json的方法步骤

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Python中内置了json库,用起来超级方便,json现在以成为开发的必备。

python对象到json字符串的转换规则:

Python JSON
dict object
list, tuple array
str, unicode string
int, long, float number
True true
False false
None null

json字符串到python对象的转换规则:

JSON Python
object dict
array list
string unicode
number (int) int, long
number (real) float
true True  
false False
null None

json的api有下面4个:

注意:dict也可以是类对象

dict转换为json

import json

person = {
  'name': 'jack',
  'age': 15,
  'email': 'jack@litets.com'
}


print('dict:', person)

person_json = json.dumps(person) # 转换为json

print('json:', person_json)

输出:

dict: {'name': 'jack', 'age': 15, 'email': 'jack@litets.com'}
json: {"name": "jack", "age": 15, "email": "jack@litets.com"}

json转换为dict

import json
person_dict = json.loads('{"name": "jack", "age": 15, "email": "jack@litets.com"}')

print('person dict:', person_dict)

输出:

person dict: {'name': 'jack', 'age': 15, 'email': 'jack@litets.com'}

类对象转换为json

import json

class Person:

  def __init__(self, name, age, email):
    self.name = name
    self.age = age
    self.email = email


person = Person('tom', 38, 'tom@litets.com')

person_json = json.dumps(person.__dict__)

print('person json:', person_json)

输出:

person json: {"name": "tom", "age": 38, "email": "tom@litets.com"}

json.dumps() 不能直接传递一个对象实例否则回报 TypeError: Object of type Person is not JSON serializable 错误 为了避免这个错误,我们需要修改:

import json
class Person:

  def __init__(self, name, age, email):
    self.name = name
    self.age = age
    self.email = email

# 将person转换为dict
def convert2json(person):
  return {
    'name': person.name,
    'age': person.age,
    'email': person.email
  }

person = Person('tom', 38, 'tom@litets.com')

# 第二个参数传递转换函数,或者使用default=lambda o: o.__dict__
person_json = json.dumps(person, default=convert2json)

print('person json:', person_json)

json转换为类对象

import json

class Person:

  def __init__(self, name, age, email):
    self.name = name
    self.age = age
    self.email = email


def convert2json(dict_json):
  return Person(dict_json['name'], dict_json['age'], dict_json['email'])


person = json.loads('{"name": "tom", "age": 38, "email": "tom@litets.com"}', object_hook=convert2json)

print('person:', person)

输出:

person: <__main__.Person object at 0x10a7230b8>

loads函数只能将json转换为字典,需要我们自己转换为对象。

dict/对象转换为json文件

import 
person = {"name": "tom", "age": 38, "email": "tom@litets.com"}

with open('person.json', 'w') as f:
  json.dump(person, f)

当前目录下会多一个person.json文件,内容是:

{"name": "tom", "age": 38, "email": "tom@litets.com"}

将json文件转换为dict/对象

import json
with open('person.json', 'r') as f:
  print(json.load(f))

输出:

{'name': 'tom', 'age': 38, 'email': 'tom@litets.com'}

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