Getting existing element in Set ...

[jamesladd]

Marias set allows me to say set.has(element) and it returns true/false. However, how can I get the existing element?

The situation I'm trying to deal with is a refresh of data from the server. If the element is new I add it but if it exists then I want to update it.

[jamesladd]

Essentially I want a find(element) or find(id)

[petermichaux]

There isn't anything in particular for what you describe. There is a setModel.toArray() method. You can look through the results returned by that.

maria.SetModel.prototype.find = function(fn) {
    var elements = this.toArray();
    for (var i = 0, ilen = elements.length; i < ilen; i++) {
        var element = elements[i];
        if (fn(element) {
            return element;
        }
    }
};

Using this function frequently would be an inefficient way to update all the elements. O(n^2)

If you have id attributes on these elements you could do much better to update all the elements in the set.

myApp.MySetModel.prototype.fromJSON = function(json) {
    var elements = this.toArray();
    var elementsMap = {};
    for (var i = 0, ilen = elements.length; i < ilen; i++) {
        var element = elements[i];
        elementsMap[element.getId()] = element;
    }
    var toAdd = [];
    for (var i = 0, ilen = json.length; i < ilen; i++) {
        var elementJSON = json[i];
        if (elementMap[elementJSON.id]) {
            elementMap[elementJSON.id].fromJSON(elementJSON); // an update, which could dispatch a "change" event.
        }
        else {
            toAdd.push(myApp.MyModel.createFromJSON(elementJSON));
        }
    }
    this.add.apply(this, toAdd); // dispatches only one change event on the set for all items added.
};

This approach using the id is O(n)

Please reopen if you still have more questions.