Python object (dictionary), json mutual conversion

1. Object and json mutual conversion

1.1 The api of json has the following 4:

json.loads() convert json to dict
json.dumps() convert dict to json
json.load() convert json file to dict
json.dump() convert dict to json file person.json
Note: dict is also available Is a class object

1.2 Convert dict to 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]"}

1.3 Convert json to 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]'}

1.4 Convert class objects to 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() cannot directly pass an object instance, otherwise it will report TypeError: Object of type Person is not JSON serializable. In order to avoid this error, we need to modify:

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)

1.5 Convert json to class object

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>

1.6 Convert dict/object to json file

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]"}

1.7 Convert json file to dict/object

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

# 输出
{
    
    'name': 'tom', 'age': 38, 'email': '[email protected]'}

2. The conversion rule of python object to json string:

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

3. Conversion rules from json string to python object:

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