CODEWITHSUNDEEP
node.jsinstancechild-process
Gunjan Patel
Gunjan Patel

Reputation: 2372

How to retrieve object from child_process stdout?

I want to run some process on different instance than Node server. I'm trying with child_process, I create some loop and execute child_process.

From child_process, I retrieve as Buffer and In object format like follow.

{ data: [], status: 'active', success: true }

How should I get these data as an object format?

const child = spawn('node', ['app.js']); 
child.stdout.on('data', (data) => {
    // How can I apply filter over to ignore some data
    console.log(data)   // print buffer
    console.log(data.toString())   // print some stringify Obj
});

Is there any way we can send data for child_process from app.js except console.log?

Upvotes: 1

Views: 408

Answers (1)

Terry Lennox
Terry Lennox

Reputation: 30675

If app.js is a node script it's easy to send data to the caller (and vice-versa) for example:

index.js

const child_process = require('child_process');
const appInstance = child_process.fork('app.js', [], {});
appInstance.on('message', message => {
    console.log('Message from app.js:', message, JSON.stringify(message));
});

app.js

// Send some data to caller. 
const data = { status: 'ok', message: 'hello from app.js' };
if (process.send) {
    process.send(data);
}

If you want to filter there are loads of ways of doing this. In the message handler you can switch on the message object, e.g. if (message && message.status).

Upvotes: 1

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