How to join/split objects that are one object in fact

Question

var ipRegex = require('ip-port-regex');
...
for(var i = 0; i < orgArrayWithHostsAndPorts.length; i++) {
   ipPort = ipRegex.parts(orgArrayWithHostsAndPorts[i]);
   console.log(ipPort);
   /* 
     Gives long listing
     { ip: 'firstip', port: 'firstport' }
     { ip: 'secondip', port: 'secondport' }
    */
   fs.writeFileSync('/tmp/test.json', JSON.stringify(ipPort, null, 2), 'utf-8');
}

So when I do fs.writeFileSync I see only the first object. What I really want is to property save every ip/port as set of the separate objects in the array. I can't add , to every object

If I understand you correctly, you wan to save an array of objects to the json file? — Davide Perozzi, Feb 24 '18 at 14:04
Could you please add an example of `orgArrayWithHostsAndPorts`? — oniramarf, Feb 24 '18 at 14:10
you mean, like `fs.writeFileSync('/tmp/test.json', JSON.stringify(orgArrayWithHostsAndPorts.map(item => ipRegex.parts(item)), null, 2), 'utf-8');` just in pretty and on multiple lines — Thomas, Feb 24 '18 at 15:11

LazyElephant · Accepted Answer · 2018-02-24T14:54:06.187

2

The fs.writeFileSync method will overwrite the file every time it's called. Since you're calling it once for every item in your list, only a single item will ever be in the file at the same time.

Additionally, using fs.appendFileSync would write all the objects making your file look like:

{ "ip": "firstip", "port": "firstport" }
{ "ip": "secondip", "port": "secondport" }

But this isn't valid .json. The objects would have to be contained in an array and separated by commas:

[
    { "ip": "firstip", "port": "firstport" },
    { "ip": "secondip", "port": "secondport" }
]

The easiest way I can think of to get the result you want is to map your data into a new array and then write that array to file:

ipPorts = orgArrayWithHostsAndPorts.map( data => ipRegex.parts(data));
fs.writeFileSync('/tmp/test.json', JSON.stringify(ipPorts, null, 2), 'utf-8');

edited Feb 24 '18 at 14:54

answered Feb 24 '18 at 14:18

LazyElephant

484
2
8

I get orgArrayWithHostsAndPorts is not a function. And it is in fact not a function, but array `[ 'firstip:firstport', 'secondip:secondport' ]` – user9405843 Feb 24 '18 at 14:51
Sorry, forgot to write map, fixed – LazyElephant Feb 24 '18 at 14:53
Thanks for saving the day! – user9405843 Feb 24 '18 at 14:57

score 0 · Answer 2 · answered Feb 24 '18 at 14:20

0

The file is opened in write mode and hence you are overwriting on every execution of the for loop. Better way is to open the file in append mode and write the contents. Look at How to append to a file in Node?

answered Feb 24 '18 at 14:20

Sandesh

487
1
3
8

How to join/split objects that are one object in fact

2 Answers2