Write Read from and to a json file

Question

I'm working on a project IN PYTHON where I need to read and write from and to a JSON file.

The JSON file's contents look like this:

{
  "buildings": [
    {
      "name": "Trump Towers",
      "nr": "1",
      "worth": "399"
    },
    {
      "name": "Penning Towers",
      "nr": "2",
      "worth": "299"
    }
  ],
  "staff": [
    {
      "name": "D Trump",
      "nr": "1",
      "worth": "399"
    },
    {
      "name": "Mr Henry",
      "nr": "2",
      "worth": "299"
    }
  ]
}

Again, I need to be able to read, add and delete the individual buildings' and staff members' data

(THE FOLLOWING IS NOT IN CORRECT SYNTAX, BUT THAT'S WHY I'M ASKING, I NEED HELP WITH THIS)

(syntax not accurate) eg.

>>> read name of building nr 1
Trump Towers

>>> delete 'Trump Towers' from buildings (output to the file)
{
  "buildings": [
    {
      "name": "Penning Towers",
      "nr": "2",
      "worth": "299"
    }
  ],
  "staff": [
    {
      "name": "D Trump",
      "nr": "1",
      "worth": "399"
    },
    {
      "name": "Mr Henry",
      "nr": "2",
      "worth": "299"
    }
  ]
}

>>> set 'Penning Towers' from buildings nr to 1
{
  "buildings": [
    {
      "name": "Penning Towers",
      "nr": "1",
      "worth": "299"
    }
  ],
  "staff": [
    {
      "name": "D Trump",
      "nr": "1",
      "worth": "399"
    },
    {
      "name": "Mr Henry",
      "nr": "2",
      "worth": "299"
    }
  ]
}

>>> add 'Jake' with nr '3' and worth  '999' to staff

{
  "buildings": [
    {
      "name": "Penning Towers",
      "nr": "1",
      "worth": "299"
    }
  ],
  "staff": [
    {
      "name": "D Trump",
      "nr": "1",
      "worth": "399"
    },
    {
      "name": "Jake",
      "nr": "2",
      "worth": "299"
    },
    {
      "name": "Mr Henry",
      "nr": "3",
      "worth": "999"
    }
  ]
}

JSON is nothing mysterious in Python; it just deserializes to nested lists and dictionaries. How would you go about processing this in pure Python? — roganjosh
– roganjosh, Commented Nov 22, 2018 at 20:06

Filip Młynarski · Accepted Answer · 2018-11-22 20:58:11Z

You can use json library to load json from your file as python dict and then modify that json and save it back as file.

import json

# Open json file and load its content as python dict
file = open('data.json', 'r')
my_json = json.loads(file.read())
file.close()

# Do stuff with that json
del my_json['buildings'][0]
my_json['buildings'][0]['Penning Towers'] = 1
my_json['staff'].append({'name': 'Jake', 'nr': '3', 'worth': '299'})

# Override json file with modified json
file = open('data.json', 'w')
file.write(json.dumps(my_json, indent=4))
file.close()

data.json after running our code:

{
    "staff": [
        {
            "nr": "1",
            "worth": "399",
            "name": "D Trump"
        },
        {
            "nr": "2",
            "worth": "299",
            "name": "Mr Henry"
        },
        {
            "nr": "3",
            "worth": "299",
            "name": "Jake"
        }
    ],
    "buildings": [
        {
            "nr": "1",
            "worth": "299",
            "name": "Penning Towers"
        }
    ]
}

Adam · Accepted Answer · 2020-02-05 19:39:18Z

2

You can use the json module to load the file with json.load() in to a Python Dictionary:

import json

f = open('file.json', 'r')
d = json.load(f)

Once it's a python dict, you can modify it as you like.

You can then write the the json to a file with json.dump(d, open('file.out', 'w'))

edited Feb 5, 2020 at 19:39

answered Nov 22, 2018 at 20:07

Adam

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