Parsing through JSON file with JAVA-SCRIPT

Question

I have a json file that looks something like this. I need to write a JS code that will parse through this file and read specific elements of the file like sensor_state of the first element and write to the specific element like change the sensor_state of "sensor_id": "302CEM/lion/light1" to on. this is what i have tried. I had a few thoughts on how to to go about it. trying to treat it like an array, sensor_state[0] will mean the first group, sensor_state[1] would mean the second one and so on. the other way is to have a name i.e light_1 before each group/object to have code that says sensor_data[light1][sensor_state] = "off" but i am unable to structure the json file to do either. Any suggestions

            {
                "sensor_data": [

                    {
                        "sensor_id": "302CEM/lion/light1",
                        "sensor_state": "off"
                    },
                    {
                        "sensor_id": "302CEM/lion/light2",
                        "sensor_state": "off"
                    }
                ]
            }

            const fs =
            require('fs');

            var data = []

            //To Read from the JSON File, dont know if this still needed

            fs.readFile('datajson.json', (err,data) => {

            if (err) throw err;

            var sensor = JSON.parse(data);

            var stringy = JSON.stringify(data)

            console.log(stringy.sensor_state[0]);

            }
            )

score 1 · Accepted Answer · answered Feb 12 '19 at 23:06

In order to process your JSON, it's much easier to do it just after JSON.parse instead of working with the string that JSON.stringify returns.
And to write your file after processing. You first convert your object into a string using JSON.stringify. Then call fs.writeFile to actually write the content

Your code will look like this

const fs = require('fs');
const fileName = './data.json';

fs.readFile(fileName, (errRead, content) => {
  if (ererrReadr) throw errRead;

  let data = JSON.parse(content);

  // Change the "sensor_id" of the first item in "sensor_data"
  data.sensor_data[0].sensor_id = 'this is a new ID';

  // Write back new JSON
  fs.writeFile(fileName, JSON.stringify(data), errWrite => {
    if (errWrite) throw errWrite;

    console.log('New data has been saved');
  });
});

Note

I had a few thoughts on how to to go about it. trying to treat it like an array

It is an array, so it only makes sense to treat it like one.

Parsing through JSON file with JAVA-SCRIPT

1 Answers1

Note