Python对象转换为json的方法步骤

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：

json字符串到python对象的转换规则：

json的api有下面4个：

• json.loads() 将json转换为dict
• json.dumps() 将dict转换为json
• json.load() 将json文件转换为dict
• json.dump() 将dict转换为json文件 person.json

注意：dict也可以是类对象

dict转换为json

import json

person = {
  'name': 'jack',
  'age': 15,
  'email': '[email protected]'
}


print('dict：', person)

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

print('json：', person_json)

输出:

dict： {'name': 'jack', 'age': 15, 'email': '[email protected]'}
json： {"name": "jack", "age": 15, "email": "[email protected]"}

json转换为dict

import json
person_dict = json.loads('{"name": "jack", "age": 15, "email": "[email protected]"}')

print('person dict:', person_dict)

输出:

person dict: {'name': 'jack', 'age': 15, 'email': '[email protected]'}

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, '[email protected]')

person_json = json.dumps(person.__dict__)

print('person json:', person_json)

输出:

person json: {"name": "tom", "age": 38, "email": "[email protected]"}

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, '[email protected]')

# 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": "[email protected]"}', 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": "[email protected]"}

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": "[email protected]"}

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': '[email protected]'}