Don't really know how to work with json files

Question

I have a little problem. I don't know much about json and I need help. I have main.py file and the .json file. I, for example, want to output a certain line from .json file in print() in main.py. For Example, the json file has the line "name":"Alex" and the second line "name":"John". I need to make sure that it finds the line "name":" Alex" in the json file and outputs the name Alex in main.py. I hope I have made my question clear

So this is a piece of json file. It's Schedule of university

"group": "КМБО-02-19",
      "days": [
        {
          "day": "ПН",
          "pars": [
            {
              "name": "Введение в ПД",
              "type": "зачет",
              "number": 3,
              "place": "Б-209",
              "whiteWeek": 17
            }
          ]
        },
        {
          "day": "ВТ",
          "pars": [
            {
              "name": "Программирование в ЗР",
              "number": 2,
              "place": "Б-209",
              "type": "зачет",
              "whiteWeek": 17
            },
            {
              "name": "Физкультура и спорт",
              "type": "зачет",
              "number": 5,
              "whiteWeek": 17
            }
          ]
        }

Why the name Alex? What is the overall structure of the JSON file? — kynnemall, Apr 22 '20 at 11:28
A JSON file is not about single lines. It defines a whole datastructure. Read the file with the `json` module and then access the values you want. How to do that depends on the type of the structure. It might be a single list, but it could be something like a list in a dictionary in a dictionary in a list. — Matthias, Apr 22 '20 at 11:28
[json is a documented format](https://www.json.org/json-en.html) and [there's a json package in the stdlib](https://docs.python.org/3/library/json.html) to unserialize json strings to Python objects. Once you have unserialzed your json to Python, it's just plain python dicts and lists stuff. — bruno desthuilliers, Apr 22 '20 at 11:44

RaidasGrisk · Answer 1 · 2020-04-22T16:26:36.560

An example tailored exactly to OPs question edit:

import json

# read the json
# with open('data.txt') as f:
    # json_data = json.load(f)

json_data = {
    "group": "КМБО-02-19",
    "days": [
    {
      "day": "ПН",
      "pars": [
        {
          "name": "Введение в ПД",
          "type": "зачет",
          "number": 3,
          "place": "Б-209",
          "whiteWeek": 17
        }
      ]
    },
    {
      "day": "ВТ",
      "pars": [
        {
          "name": "Программирование в ЗР",
          "number": 2,
          "place": "Б-209",
          "type": "зачет",
          "whiteWeek": 17
        },
        {
          "name": "Физкультура и спорт",
          "type": "зачет",
          "number": 5,
          "whiteWeek": 17
        }
      ]
    }]}

# loop over each day and pars inside it
for day in json_data['days']:
    for par in day['pars']:

        # check if Alex and print
        if par['name'] == 'Alex':
            print(par['name'])

GuillemVS · Answer 2 · 2020-04-22T12:00:02.087

0

I think that this was already answered here: multiple Json objects in one file extract by python.

Where u can see how to store multiple objects in a file:

[
{"ID":"12345","Timestamp":"20140101", "Usefulness":"Yes",
  "Code":[{"event1":"A","result":"1"},…]},
{"ID":"1A35B","Timestamp":"20140102", "Usefulness":"No",
  "Code":[{"event1":"B","result":"1"},…]},
{"ID":"AA356","Timestamp":"20140103", "Usefulness":"No",
  "Code":[{"event1":"B","result":"0"},…]},
...
]

And later on load them:

import json

with open('file.json') as json_file:

data = json.load(json_file)

Where data is a python list of dicts (as bruno-desthuilliers pointed out):

data[index]["name"]

edited Apr 22 '20 at 12:00

answered Apr 22 '20 at 11:38

GuillemVS

356
1
13

1

"Where data is an json object array" => nope, it's a Python list of dicts. – bruno desthuilliers Apr 22 '20 at 11:50
Thanks, I just guessed what it would be I dont use python. – GuillemVS Apr 22 '20 at 12:00

Sudip Ghimire · Answer 3 · 2020-04-22T11:38:42.387

-1

While I am not a python guy. If I had to do that in c++ I would create own parser for JSON file and create a Token tree with all it's property and then use that as your library.

or

Read the docs

or

invert bit time to get the JSON parser made by other fellows

or

see the same question at stackoverflow

edited Apr 22 '20 at 11:38

answered Apr 22 '20 at 11:33

Sudip Ghimire

677
6
15

I don't know if reinventing the wheel is a tradition amongst c++ programmers, but I'm pretty sure there are working, maintained C++ json parsers already... – bruno desthuilliers Apr 22 '20 at 11:38
And that's what i am talking about. You can get any prebuild parsers and head on to the documentation provided – Sudip Ghimire Apr 22 '20 at 11:46
"If I had to do that in c++ I would create own parser for JSON" ;-) (but I was mostly nitpicking you, sorry ) – bruno desthuilliers Apr 22 '20 at 11:52
No problem. By the way the answer of @GuillemVs seems to be working even I hadn't tried – Sudip Ghimire Apr 22 '20 at 11:55
Yep, it _should_ be working - assuming he correctly guessed what the OP's data really look like of course... – bruno desthuilliers Apr 22 '20 at 13:32

Don't really know how to work with json files

3 Answers3