JSON file handles object Tags

json Document processing ：

What is? json：

JSON(JavaScript Object Notation, JS Object tag ) Is a lightweight data exchange format . It's based on ECMAScript (w3c To formulate the js standard ) A subset of , Use text format completely independent of programming language to store and represent data . A simple and clear hierarchy makes JSON Become the ideal data exchange language . Easy to read and write , At the same time, it is also easy for machine analysis and generation , And effectively improve the network transmission efficiency .Pycharm

JSON Support data format ：

1. object （ Dictionaries ）. Use curly braces .
2. Array （ list ）. Use square brackets .
3. plastic 、 floating-point 、 Boolean types also have null type .
4. String type （ The string must be in double quotation marks , You can't use single quotes ）.

Use commas to separate multiple data . Be careful ：json It's essentially a string .

Dictionary and list transfer JSON：

import json

books = [
    {
        'title': ' How steel is made ',
        'price': 9.8
    },
    {
        'title': ' A dream of red mansions ',
        'price': 9.9
    }
]

json_str = json.dumps(books,ensure_ascii=False)
print(json_str)

because json stay dump When , Only store ascii The characters of , Therefore, Chinese will be escaped , At this time, we can use ensure_ascii=False Turn off this feature . stay Python in . Only basic data types can be converted to JSON Format string . That is to say ：int、float、str、list、dict、tuple.

take json Data direct dump To a file ：

json In addition to dumps function , One more dump function , This function can pass in a file pointer , Directly string dump To a file . The sample code is as follows ：

books = [
    {
        'title': ' How steel is made ',
        'price': 9.8
    },
    {
        'title': ' A dream of red mansions ',
        'price': 9.9
    }
]
with open('a.json','w') as fp:
    json.dump(books,fp)

Will a json character string load become Python object ：

json_str = '[{"title": " How steel is made ", "price": 9.8}, {"title": " A dream of red mansions ", "price": 9.9}]'
books = json.loads(json_str,encoding='utf-8')
print(type(books))
print(books)

Read directly from file json：

import json
with open('a.json','r',encoding='utf-8') as fp:
    json_str = json.load(fp)
    print(json_str)