JSON

https://pynative.com/python-json-exercise/

Json 표준에는 겹따옴표가 표준이고 홑따옴표가 비표준이라는 것

vsCode에서 JSON파일

vscode ~ new file ~ select language : json

~ Shift+Option(alt)+ F ==> json 예쁘게 보기

dictionary -> json 문자열 :: json.dump()

http://b1ix.net/402

json.dump() vs. json.dumps()

dump() 함수: Python객체를 JSON “파일”에 저장하기

dumps() 함수: Python객체를 JSON “문자열”로 변환

https://www.delftstack.com/ko/howto/python-pandas/json-to-pandas-dataframe/

더블쿼테이션이 표준

{ "1": "one", "2": "둘", "삼": "셋"}

{'1':'one', '2':'둘', '삼':'셋'}

import json

# read : 파일 전체
# readline: 한라인데이터
# readlines: 전체데이터를 라인단위로 

# data = '{"1":"one", "2":"둘", "삼":"셋"}'    # str
with open('../app/data/mobi-ex1.json', 'r') as line:
    data = line.read()

s2d = json.loads(data)
# {'1': 'one', '2': '둘', '삼': '셋'}          # dict

d2s = json.dumps(s2d)
# '{"1": "one", "2": "\\\\ub458", "\\\\uc0bc": "\\\\uc14b"}'  # str
d2s_ko = json.dumps(s2d, ensure_ascii=False)
# '{"1": "one", "2": "둘", "삼": "셋"}'


# data = "{'1':'one', '2':'둘', '삼':'셋'}"    # str
with open('../app/data/mobi-ex1-single_quote.txt', 'r') as line:
    data = line.read()

s2d = json.loads(data)
# JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)
s2d = json.loads(data.replace("'", "\\""))

json문자열 -> dictionary :: json.load()

json.load() vs. json.loads()

load() 함수: JSON “파일”을 Python객체로 불러오기

loads() 함수: JSON “문자열”을 Python객체로 변환

json.load(
    fp, 
    *, cls=None, 
    object_hook=None, 
    parse_float=None, 
    parse_int=None,
    parse_constant=None,
    object_pairs_hook=None,
    **kw)

json.loads(
    s, 
    *, cls=None, 
    object_hook=None, 
    parse_float=None, 
    parse_int=None, 
    parse_constant=None,
    object_pairs_hook=None,
    **kw)

에러

AttributeError: ‘str’ object has no attribute ‘loads’

=> json.load()와 json.loads()를 구별못했거나, json이름을 변수로 사용한 경우

json 예제

{"id": 2, "name": ["def", "qwe"]}
{"id": 3, "name": ["def", "asd"]}
{"id": 4, "name": ["def", "zxc"]}
...

import json
basePath = '../app/data/mobi_data'
filePath = basePath + '/mobi1/mobility1_01.json'

# json_data = open(filePath)
# data = json.load(json_data)
data = []
with open(filePath) as multiLines:
    for line in multiLines:
        data.append(json.loads(line))

read inline json

import json

inline_JSON = '{"id":1, "name": ["abc", "xyz"]}'
jsonData = json.loads(inline_JSON)

#----------------------------------------------------------
len(jsonData)  # 2
type(jsonData) # dict
jsonData.keys()      # dict_keys(['id', 'name'])
jsonData.get("name") # ['abc', 'xyz']
json.dumps(jsonData) # '{"id": 1, "name": ["abc", "xyz"]}'
print(json.dumps(jsonData, indent='\\t'))
# {
#\t"id": 1,
#\t"name": [
#\t\t"abc",
#\t\t"xyz"
#\t]
#}

read json Files

{
    "id": 2, 
    "name": ["def", "qwe"]
}

path_JSON = './jsondata/jsn2.json' # String

### Read File 
jsonFile = open(path_JSON,'r') #'r'ead,'w'rite,'a'ppend
jsonData = json.load(jsonFile)
jsonFile.close()

### Read File 
# with문을 나올 때 close를 자동으로 불러줍니다.
with open(path_JSON) as jsonFile:
    jsonData = json.load(jsonFile)

JSON parse

### JSON (JavaScript Object Notation)
# https://docs.python.org/3/library/json.html#json.dumps

import json

# Read string
json_string='{"title": "example", "age": 38, "married": true}'
contents = json.loads(json_string)
# pretty
print(json.dumps(contents, sort_keys=True ,indent=2))

# Load file
with open('./text.json') as json_file:
    contents = json.load(json_file)

print(json.dumps(contents, indent=4, ensure_ascii=False))

# Write JSON 
with open('./data.json', 'w') as json_file:
    json.dump(json_string, json_file)

# parse 1 value
val = contents["title"]
val = contents.get("title")
print(f'value=> {val}')

# json  to  python
# object to dictionaries
# arrays to lists
# Null to None
valList = contents.get("house").get("json_array")
for val in valList:
    print(val)

valDic = contents.get("house").get("json_object")
valDic.keys()
valDic.values()
for key in valDic:
    print(key, valDic[key])
for key, val in valDic.items():
    print(key, val)
for item in valDic.items():
    print(item)

# search with JMES Path
import jmespath
jmespath.search("persons[*].age", contents)
jmespath.search("house.json_object.name", contents)

{
    "title": "json_example",
    "house" : {
        "json_string": "string_example",
        "json_number": 100,
        "json_array": [1, 2, 3, 4, 5],
        "json_object": { "name":"John", "age":30},
        "json_bool": true
    },
    "house1" : {
        "json_string": "string_example",
        "json_number": 100,
        "json_array": [1, 2, 3, 4, 5],
        "json_object": { "name":"John", "age":30},
        "json_bool": true
    },
    "한글" : "그럴겁니다",
    "persons": [
        { "name": "erik", "age": 38 },
        { "name": "john", "age": 45 },
        { "name": "rob", "age": 14 }
    ]
}

Error

JSONDecodeError: Expecting property name enclosed in double quotes: line 2 column 1 (char 2)