无法使Firebase update（）与提供的对象一起使用

Question

Ok, so after a lot of trial and error I have to try asking here. I'm trying to update a Firebase entry and my code look like this,

This is from my service.js:

//This dosn't work
var updateItem = function (item, id) {
    var ref  = new Firebase(FIREBASE_URI + '/lessons/' + id);
    ref.$update(item);
}

//This works (items is a ref to new Firebase(FIREBASE_URI + '/lessons/');
var addItem = function (item) {
    items.$add(item);
}

And this is from my controller:

$scope.updateLesson = function (item) {
    LessonsService.updateLesson(item, id);
}

The error I'm getting is this:

Error: Firebase.set failed: First argument contains an invalid key ($id). Keys must be non-empty strings and can't contain ".", "#", "$", "/", "[", or "]"

The object I'm passing in looks like this:

Object {
    $id: "-JLIUvVMLqoCVgHaed9f", 
    $bind: function, $add: function, $save: function,     $set: function…}
    $add: function (item) {
    $auth: function (token) {
    $bind: function (scope, name, defaultFn) {
    $child: function (key) {
    $getIndex: function () {
    $getRef: function () {
    $id: "-JLIUvVMLqoCVgHaed9f"
    $off: function (type, callback) {
    $on: function (type, callback) {
    $remove: function (key) {
    $save: function (key) {
    $set: function (newValue) {
    $transaction: function (updateFn, applyLocally) {
    $update: function (newValue) {
    createDate: "2014-04-24T11:29:42.692Z"
    desc: "test"
    somemorevalues: "here"
}

I have tried to do a JSON.stringify on the object and got a nice looking result looking like this:

 {
  createDate: "2014-04-24T11:29:42.692Z",
  desc: "test",
  somemorevalues: "here"
 }

But it wont accept it when I'm passing that in thru a variable. (Error: Firebase.update failed: First argument must be an object containing the children to replace.) If I pass it in directly as a string it works thou (?!!!). It's the exact same information in the variable.. What the hell am I missing?! As of now I'm building my own object like this:

 var newItem = {
     title: item.title,
     desc: item.desc,
     ingress: item.ingress,
     workarea: item.workarea,
     years: {val: item.years.val},
 }

and passing that along to firebase, which works but is not ideal because its "static".

Answer 1

Use angularFire according to the API . Read the Angular+Firebase Overview for a good primer.

In essence, instead of passing angularFire objects into a Firebase ref (which will not work since keys may not have a $ in the name) and calling update/set yourself, simply use the $set / $update methods already available on the $firebase object:

var ref = $firebase(URL);
ref[id].desc = 'foo';
ref.$save(id).then(onComplete);

Answer 2

Not sure if its just a typo but you've got a comma after the years value (removed it below).

var newItem = {
    title: item.title,
    desc: item.desc,
    ingress: item.ingress,
    workarea: item.workarea,
    years: {val: item.years.val}
 }

As it thinks that its trying to pass an empty key after years, therefor giving the error.