How to return a complex JSON response with Node.js?


Using nodejs and express, I'd like to return one or multiple objects (array) using JSON. In the code below I output one JSON object at a time. It works but this isn't exactly what I want. The response produced isn't a valid JSON response since I have many objects.

I am well aware that I could simply add all objects to an array and return that specific array in res.end. However I am afraid this could become heavy to process and memory intensive.

What is the proper way to acheive this with nodejs? Is query.each the right method to call?

app.get('/users/:email/messages/unread', function(req, res, next) {
    var query = MessageInfo
        .find({ $and: [ { 'email': }, { 'hasBeenRead': false } ] });

    res.writeHead(200, { 'Content-Type': 'application/json' });   
    query.each(function(err, msg) {
        if (msg) { 
            res.write(JSON.stringify({ msgId: msg.fileName }));
        } else {

This question is tagged with json node.js express mongoose

~ Asked on 2012-01-18 05:28:36

The Best Answer is


On express 3 you can use directly res.json({foo:bar})

res.json({ msgId: msg.fileName })

See the documentation

~ Answered on 2012-11-22 11:21:58


I don't know if this is really any different, but rather than iterate over the query cursor, you could do something like this:

query.exec(function (err, results){
  if (err) res.writeHead(500, err.message)
  else if (!results.length) res.writeHead(404);
  else {
    res.writeHead(200, { 'Content-Type': 'application/json' });
    res.write(JSON.stringify( (msg){ return {msgId: msg.fileName}; })));

~ Answered on 2012-01-18 14:46:34

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