nodejs - first argument must be a string or Buffer - when using response.write with http.request

Question

nodejs - first argument must be a string or Buffer - when using response.write with http.request

I'm simply trying to create a node server that outputs the HTTP status of a given URL.

When I try to flush the response with res.write, I get the error: throw new TypeError('first argument must be a string or Buffer');

But if I replace them with console.log, everything is fine (but I need to write them to the browser not the console).

The code is

var server = http.createServer(function (req, res) {
    res.writeHead(200, {"Content-Type": "text/plain"});

    request({
        uri: 'http://www.google.com',
        method: 'GET',
        maxRedirects:3
    }, function(error, response, body) {
        if (!error) {
            res.write(response.statusCode);
        } else {
            //response.end(error);
            res.write(error);
        }
    });     

    res.end();
});
server.listen(9999);

I believe I should add a callback somewhere but pretty confused and any help is appreciated.

node.js
http
callback

Answer 1

response.statusCode is a number, e.g. response.statusCode === 200, not '200'. As the error message says, write expects a string or Buffer object, so you must convert it.

res.write(response.statusCode.toString());

You are also correct about your callback comment though. res.end(); should be inside the callback, just below your write calls.

Answer 2

Well, obviously you are trying to send something which is not a string or buffer. :) It works with console, because console accepts anything. Simple example:

var obj = { test : "test" };
console.log( obj ); // works
res.write( obj ); // fails

One way to convert anything to string is to do that:

res.write( "" + obj );

whenever you are trying to send something. The other way is to call .toString() method:

res.write( obj.toString( ) );

Note that it still might not be what you are looking for. You should always pass strings/buffers to .write without such tricks.

As a side note: I assume that request is a asynchronous operation. If that's the case, then res.end(); will be called before any writing, i.e. any writing will fail anyway ( because the connection will be closed at that point ). Move that line into the handler:

request({
    uri: 'http://www.google.com',
    method: 'GET',
    maxRedirects:3
}, function(error, response, body) {
    if (!error) {
        res.write(response.statusCode);
    } else {
        //response.end(error);
        res.write(error);
    }
    res.end( );
});

Answer 3

Request takes a callback method, its async! So I am assuming, by the time the callback is executed the res.end() might get called. Try closing the request within the callback?!