Get line number while parsing a JSON file

Question

I am using google Gson library to parse JSON files, which are ipython note book files. Is it possible to collect the line number where a JSON object or array starts or end.

JsonReader reader = new JsonReader(new FileReader(notebookFile));
    Gson gson = new GsonBuilder().create();
    // Read file in stream mode
    reader.beginObject();
    while (reader.hasNext()) {
        String name = reader.nextName();
        if (name.equals("cells")) {
            //can we determine line number of name
            reader.beginArray();
            .....
         }
        ....
    }

Part of a notebook:

"metadata": {
  "name": "5-Scatterplots"
 },
 "nbformat": 3,
 "nbformat_minor": 0,
 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import pandas as pd\n",
      "store = pd.HDFStore('/Volumes/FreshBooks/data/store.h5')\n",
      "may07 = store['may07']\n",
      "may08 = store['may08']"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 1
    },

Answer 1

Full disclosure: I'm the maintainer of the package below.

There is now a new Python package that solves this use case: https://github.com/open-alchemy/json-source-map

Installation: pip install json_source_map

For example, in your case:

from json_source_map import calculate

source = '''
{
  "metadata": {
    "name": "5-Scatterplots"
  },
  "nbformat": 3,
  "nbformat_minor": 0,
  "worksheets": [
    {
      "cells": [
        {
          "cell_type": "code",
          "collapsed": false,
          "input": [
            "import pandas as pd\\n",
            "store = pd.HDFStore('/Volumes/FreshBooks/data/store.h5')\\n",
            "may07 = store['may07']\\n",
            "may08 = store['may08']"
          ],
          "language": "python",
          "metadata": {},
          "outputs": [],
          "prompt_number": 1
        }
      ]
    }
  ]
}
'''

print(calculate(source))

This prints:

{
    "": Entry(
        value_start=Location(line=1, column=0, position=1),
        value_end=Location(line=27, column=1, position=568),
        key_start=None,
        key_end=None,
    ),
    "/metadata": Entry(
        value_start=Location(line=2, column=14, position=17),
        value_end=Location(line=4, column=3, position=51),
        key_start=Location(line=2, column=2, position=5),
        key_end=Location(line=2, column=12, position=15),
    ),
    "/metadata/name": Entry(
        value_start=Location(line=3, column=12, position=31),
        value_end=Location(line=3, column=28, position=47),
        key_start=Location(line=3, column=4, position=23),
        key_end=Location(line=3, column=10, position=29),
    ),
    "/nbformat": Entry(
        value_start=Location(line=5, column=14, position=67),
        value_end=Location(line=5, column=15, position=68),
        key_start=Location(line=5, column=2, position=55),
        key_end=Location(line=5, column=12, position=65),
    ),
    "/nbformat_minor": Entry(
        value_start=Location(line=6, column=20, position=90),
        value_end=Location(line=6, column=21, position=91),
        key_start=Location(line=6, column=2, position=72),
        key_end=Location(line=6, column=18, position=88),
    ),
    "/worksheets": Entry(
        value_start=Location(line=7, column=16, position=109),
        value_end=Location(line=26, column=3, position=566),
        key_start=Location(line=7, column=2, position=95),
        key_end=Location(line=7, column=14, position=107),
    ),
    "/worksheets/0": Entry(
        value_start=Location(line=8, column=4, position=115),
        value_end=Location(line=25, column=5, position=562),
        key_start=None,
        key_end=None,
    ),
    "/worksheets/0/cells": Entry(
        value_start=Location(line=9, column=15, position=132),
        value_end=Location(line=24, column=7, position=556),
        key_start=Location(line=9, column=6, position=123),
        key_end=Location(line=9, column=13, position=130),
    ),
    "/worksheets/0/cells/0": Entry(
        value_start=Location(line=10, column=8, position=142),
        value_end=Location(line=23, column=9, position=548),
        key_start=None,
        key_end=None,
    ),
    "/worksheets/0/cells/0/cell_type": Entry(
        value_start=Location(line=11, column=23, position=167),
        value_end=Location(line=11, column=29, position=173),
        key_start=Location(line=11, column=10, position=154),
        key_end=Location(line=11, column=21, position=165),
    ),
    "/worksheets/0/cells/0/collapsed": Entry(
        value_start=Location(line=12, column=23, position=198),
        value_end=Location(line=12, column=28, position=203),
        key_start=Location(line=12, column=10, position=185),
        key_end=Location(line=12, column=21, position=196),
    ),
    "/worksheets/0/cells/0/input": Entry(
        value_start=Location(line=13, column=19, position=224),
        value_end=Location(line=18, column=11, position=425),
        key_start=Location(line=13, column=10, position=215),
        key_end=Location(line=13, column=17, position=222),
    ),
    "/worksheets/0/cells/0/input/0": Entry(
        value_start=Location(line=14, column=12, position=238),
        value_end=Location(line=14, column=35, position=261),
        key_start=None,
        key_end=None,
    ),
    "/worksheets/0/cells/0/input/1": Entry(
        value_start=Location(line=15, column=12, position=275),
        value_end=Location(line=15, column=72, position=335),
        key_start=None,
        key_end=None,
    ),
    "/worksheets/0/cells/0/input/2": Entry(
        value_start=Location(line=16, column=12, position=349),
        value_end=Location(line=16, column=38, position=375),
        key_start=None,
        key_end=None,
    ),
    "/worksheets/0/cells/0/input/3": Entry(
        value_start=Location(line=17, column=12, position=389),
        value_end=Location(line=17, column=36, position=413),
        key_start=None,
        key_end=None,
    ),
    "/worksheets/0/cells/0/language": Entry(
        value_start=Location(line=19, column=22, position=449),
        value_end=Location(line=19, column=30, position=457),
        key_start=Location(line=19, column=10, position=437),
        key_end=Location(line=19, column=20, position=447),
    ),
    "/worksheets/0/cells/0/metadata": Entry(
        value_start=Location(line=20, column=22, position=481),
        value_end=Location(line=20, column=24, position=483),
        key_start=Location(line=20, column=10, position=469),
        key_end=Location(line=20, column=20, position=479),
    ),
    "/worksheets/0/cells/0/outputs": Entry(
        value_start=Location(line=21, column=21, position=506),
        value_end=Location(line=21, column=23, position=508),
        key_start=Location(line=21, column=10, position=495),
        key_end=Location(line=21, column=19, position=504),
    ),
    "/worksheets/0/cells/0/prompt_number": Entry(
        value_start=Location(line=22, column=27, position=537),
        value_end=Location(line=22, column=28, position=538),
        key_start=Location(line=22, column=10, position=520),
        key_end=Location(line=22, column=25, position=535),
    ),
}

This tells you the line, column and character position for the start and end location for each value in the JSON document.

Answer 2

You can accomplish this in python using https://pypi.org/project/json-cfg/

Here's a recursive strategy for printing the line number for each key and each value.

import jsoncfg
from jsoncfg.config_classes import ConfigJSONObject, ConfigJSONArray, ConfigJSONScalar


def recursivePrint(element):
    if isinstance(element, ConfigJSONObject):
        # Dictionary
        for key, value in element:
            print(f"key   \"{key}\" at line {jsoncfg.node_location(element[key]).line}")
            recursivePrint(element[key])
    elif isinstance(element, ConfigJSONArray):
        # Array
        for item in element:
            recursivePrint(item)
    elif isinstance(element, ConfigJSONScalar):
        value = element()
        if isinstance(value, str):
            value = value.strip()

        print(f"value \"{value}\" at line {jsoncfg.node_location(element).line}")


parsed = jsoncfg.load_config("example.json")
recursivePrint(parsed)

Screenshot of results