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:
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:
- 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': '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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