Read and Write to JSON-Files

[martink...@gmail.com]

Hi,

I want to read and write json files. I'm new with nodejs so I don't have much experience.

This is the content of my file and the structure:

{

   "products": {

       "1234": {

           "states": {

               "STATEA": 0,

               "STATEB": 0,

               "STATEC": 0

           },

           "emailContacts": [

               "te...@test.de",

               "te...@test2.de"

           ]

       },

       "1256734": {

           "states": {

               "STATEA": 0,

               "STATEB": 0,

               "STATEC": 0

           },

           "emailContacts": [

              "te...@test.de",

              "te...@test2.de"

           ]

       }

   }

}

I use this file because actually I dont't use a database. 

Now I have a nodejs app which read states from receiving messages, if one state is not normal I want to change the value of the state in the json file ad save the state there. For this I tried this code:

var file = require('./data.json')

console.dir(file.products['1234'].states['STATEA']);

file.products['1234'].states['STATEA']=5;

console.dir(file.products['1234'].states['STATEA']);

It seems to work, but after stopping the nodejs app and looking into the file there is no change in the file.

I tried different things but I didn't find a solution. I think the problem is while running the app I only work on a copy of the file and not on the original file...

I want to store the states in the file for a longer time. Later I want to use a database instead a json file.

Thanks for help! :)

[Mark Volkmann]

You have to use the built-in fs module to write the new JSON back to the file. You want something like this:

const fs = require('fs');

fs.writeFile('./data.json', JSON.stringify(file), err => {

  if (err) {

    console.error(err);

  } else {

    console.log('It worked!');

  }

});

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R. Mark Volkmann

Object Computing, Inc.

[martink...@gmail.com]

I tried it with fs module and it worked.

Thanks! 

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