Backbone.js save always triggers error even on success - backbone.js

Question

I've read several of the other posts about this problem and none of the solutions seem to be working for me. I have the following code in my View:
this.model.set({
username: $('#user-username').val(),
role: $('#user-role').val(),
description: $('#user-description').val()
});
this.model.save({ user_id: this.model.get('user_id')}, {
success: function(user, response) {
console.log('success:', response);
$('.flash-message').text("Success").show();
},
error: function(user, response) {
console.log('error:', response);
$('.flash-message').text(response.error).show();
}
});
and this on my server controller (nodejs running express 3):
UserController.prototype.updateAction = function(req, res) {
if (req.route.method != "put") {
res.send({status: "error", error: "update must be put action and must include values"});
return false;
}
var query = {'user_id': req.params.id};
var user = req.body;
var userRepository = this.userRepository
// delete _id to avoid errors
delete user._id;
userRepository.update(query, user, {}, function(err, updated) {
if ((err) || (!updated)) {
res.send({"status": "error", "error": err});
return false;
}
// send updated user back
util.log('updated user ' + user.user_id);
res.setHeader('Content-Type', 'application/json');
res.status(200);
res.send(JSON.stringify({"status": "success", "updated": updated}));
});
}
On save, my model is saved correctly in the server and I have verified the server response with this. So, as far as I can tell the server is returning status 200, valid JSON, with a valid JSON response header. And yet my backbone model.save function always triggers the error callback. Can anyone please tell me why and how to resolve this?
I am able to get this to work if set the dataType to text like so:
this.model.save({ user_id: this.model.get('user_id')}, {
dataType: "text",
success: function(user, response) {
console.log('success:', response);
$('.flash-message').text("Success").show();
},
error: function(user, response) {
console.log('error:', response);
$('.flash-message').text(response.error).show();
}
});
but doing so does not allow me to get the response back from the server. Instead I get this in the response var:
success: {
"_id": "5133b02062e15ed1d2000001",
}

Answer 1

Backbone expects to get back the model that it sent in its PUT or POST request body.
Instead of:
res.send(JSON.stringify({"status": "success", "updated": updated}));
Try this in your server's response:
res.json(user);

Answer 2

There may be a possibility that your call may have got in state 200 connection established which backbone detects as error, Backbone throws success only when the call is 200OK.

Answer 3

What's your server code? You need to make sure you're sending json back to backbone like so:
//In your express POST route
user.save(function(err) {
if(err){
console.log(err);
return res.json(401);
} else {
console.log('user: ' +user.username + ' saved');
return res.json(200);
}
Then in your backbone view you can check for the response and do what you need:
//some function in your view
this.model.save(this.formValues, {
success: function(model, response, options) {
if (response == 200) {
console.log('success :' + response);
//Do stuff
} else {
console.log('error: '+response);
//etc.
Also note that as per the backbone model documentation:
"save accepts success and error callbacks in the options hash, which will be passed the arguments (model, response, options)"