JSON structure output

Question

I'm working on a school assignment, Node.js, and have trouble with getting my output correct. It's the res.end part that isn't working, but res.end(stdout); works. Why?

case "/status":
    /**
     * Run child process "uname -a".
     */
    cp.exec("uname -a", (error, stdout, stderr) => {
        if (error || stderr) {
            // Do something with the error(s)
            console.log("Something went wrong...", error, stderr);
        }

        // status route
        res.writeHead(200, { "Content-Type": "application/json" });
        res.end({
            "uname": stdout
        });
    });
break;

Oops, I'm so used to using Express that I didn't realize, my apologies! The answer may still be similar, however - I'll write one up and post it. — Joe Clay
– Joe Clay, Commented Mar 2, 2017 at 13:17

Joe Clay · Accepted Answer · 2017-03-02 13:29:40Z

1

As specified in the Node.js docs, res.end can only take a string or a buffer - or nothing at all - as its first parameter. If you wish to send JSON using it, you'll have to set the content type (which you've done) and stringify the object:

res.writeHead(200, { "Content-Type": "application/json" });
res.end(JSON.stringify({
    "uname": stdout
}));

This is effectively what Express.js does when you call res.send/res.json on an object.

answered Mar 2, 2017 at 13:29

Joe Clay

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2 Comments

Antti Keränen Over a year ago

Thanks for the help! I never tried putting JSON.stringify there.

Joe Clay Over a year ago

@AnttiKeränen: No problem! I think something key to bear in mind when working with Node's HTTP module is that it's a web server API, not a web application API. They don't implement higher level concerns like JSON, or authentication, etc. etc. etc. - they leave it up to you (or more likely, a framework like Express, Hapi or Restify) to decide how to implement those features in a way that fits your needs.

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