Setting data in viewModel knockoutjs from html5 websocket - html

Question

I am trying to create knockout.js component that is getting data from HTML5 Websocket. Websocket code is in separate script e.g. util.js. I am able to connect and get data from socket, but dont know how correctly to set corresponding property in component`s ViewModel.
Websocket - util.js:
var options = {
server: '127.0.0.1',
port: '12345'
};
var socket, loadedFlag;
var timeout = 2000;
var clearTimer = -1;
var data = {};
function handleErrors(sError, sURL, iLine)
{
return true;
};
function getSocketState()
{
return (socket != null) ? socket.readyState : 0;
}
function onMessage(e)
{
data=$.parseJSON(e.data);
// ???? Is it possible to have here something like
// ???? viewModel.getDataWS1(data);
}
function onError()
{
clearInterval(clearTimer);
socket.onclose = function () {
loadedFlag = false;
};
clearTimer = setInterval("connectWebSocket()", timeout);
}
function onClose()
{
loadedFlag = false;
clearInterval(clearTimer);
clearTimer = setInterval("connectWebSocket()", timeout);
}
function onOpen()
{
clearInterval(clearTimer);
console.log("open" + getSocketState());
}
function connectWebSocket()
{
if ("WebSocket" in window)
{
if (getSocketState() === 1)
{
socket.onopen = onOpen;
clearInterval(clearTimer);
console.log(getSocketState());
}
else
{
try
{
host = "ws://" + options.server + ":" + options.port;
socket = new WebSocket(host);
socket.onopen = onOpen;
socket.onmessage = function (e) {
onMessage(e);
};
socket.onerror = onError;
socket.onclose = onClose;
}
catch (exeption)
{
console.log(exeption);
}
}
}
}
Component (productDisplay.js) - creating so that is can be used on multiple pages:
define([
'jquery',
'app/models/productDisplayModel',
'knockout',
'mapping',
'socket'
],
function ($, model, ko, mapping) {
ko.components.register('product', {
viewModel: {require: 'app/models/productModel'},
template: {require: 'text!app/views/product.html'}
});
});
Product ViewModel (productModel.js) - where I struggle to set viewModel property to data from websocket:
var viewModel = {};
define(['knockout', 'mapping', 'jquery'], function (ko, mapping, $) {
function Product(name, rating) {
this.name = name;
this.userRating = ko.observable(rating || null);
}
function MyViewModel() {
this.products = ko.observableArray(); // Start empty
}
MyViewModel.prototype.getDataWS1 = function () {
//Websocket has not connected and returned data yet, so data object is empty
// ???? Is there anyway I can add something like promise so that the value is set once socket is connected?
this.products(data);
};
// apply binding on page load
$(document).ready(function () {
connectToServer1();
viewModel = new MyViewModel();
ko.applyBindings(viewModel);
viewModel.getDataWS1();
});
});
Thank you for any ideas.

Answer 1

You can update an observable when you get a message in the following manner:
util.js
function onMessage(e) {
var productData = $.parseJSON(e.data);
viewModel.addNewProduct(productData);
}
productModel.js
function Product(name, rating) {
this.name = name;
this.userRating = ko.observable(rating || null);
}
function MyViewModel() {
this.products = ko.observableArray(); // Start empty
}
MyViewModel.prototype.addNewProduct(product) {
var newProduct = new Product(product.name, product.rating);
this.products.push(newProduct);
}
Basically the idea is that when you get a message (in onMessage function), you will parse the data and call a function in your viewmodel to add the message data to the viewmodel properties (observables, observableArrays, etc.)