I'm trying to send data through a POST request from a node.js server to another node.js server. What I do in the "client" node.js is the following:

var options = {
    host: 'my.url',
    port: 80,
    path: '/login',
    method: 'POST'
};

var req = http.request(options, function(res){
    console.log('status: ' + res.statusCode);
    console.log('headers: ' + JSON.stringify(res.headers));
    res.setEncoding('utf8');
    res.on('data', function(chunk){
        console.log("body: " + chunk);
    });
});

req.on('error', function(e) {
    console.log('problem with request: ' + e.message);
});

// write data to request body
req.write('data\n');
req.write('data\n');
req.end();

This chunk is taken more or less from the node.js website so it should be correct. The only thing I don't see is how to include username and password in the options variable to actually login. This is how I deal with the data in the server node.js (I use express):

app.post('/login', function(req, res){
    var user = {};
    user.username = req.body.username;
    user.password = req.body.password;
        ...
});

How can I add those username and password fields to the options variable to have it logged in?

Thanks

Posting data is a matter of sending a query string (just like the way you would send it with an URL after the ?) as the request body.

This requires Content-Type and Content-Length headers, so the receiving server knows how to interpret the incoming data. ^(*)

var querystring = require('querystring');
var http = require('http');

var data = querystring.stringify({
      username: yourUsernameValue,
      password: yourPasswordValue
    });

var options = {
    host: 'my.url',
    port: 80,
    path: '/login',
    method: 'POST',
    headers: {
        'Content-Type': 'application/x-www-form-urlencoded',
        'Content-Length': Buffer.byteLength(data)
    }
};

var req = http.request(options, function(res) {
    res.setEncoding('utf8');
    res.on('data', function (chunk) {
        console.log("body: " + chunk);
    });
});

req.write(data);
req.end();

^(*) Sending data requires the Content-Type header to be set correctly, i.e. application/x-www-form-urlencoded for the traditional format that a standard HTML form would use.

It's easy to send JSON (application/json) in exactly the same manner; just JSON.stringify() the data beforehand.

URL-encoded data supports one level of structure (i.e. key and value). JSON is useful when it comes to exchanging data that has a nested structure.

The bottom line is: The server must be able to interpret the content type in question. It could be text/plain or anything else; there is no need to convert data if the receiving server understands it as it is.

Add a charset parameter (e.g. application/json; charset=Windows-1252) if your data is in an unusual character set, i.e. not UTF-8. This can be necessary if you read it from a file, for example.