Developing custom kendo ui widget

Question

How can I develop a custom widget behaving like this sample:

http://jsfiddle.net/anilca/u2HF7/

Here is my kickstart reading, but I could not find out how to define the templates of dropdownlists and link them together by change events.

(function($) { 
    var kendo = window.kendo,
    ui = kendo.ui,
    Widget = ui.Widget;

    var Editable = Widget.extend({
    init: function(element, options) {
       var that = this;

       Widget.fn.init.call(this, element, options);

       that._create();
    },
    options: {
       name: "Editable",
       value: " ",
       editable: false
    },
    _create: function() {
       var that = this;
       // create dropdowns from templates and append them to DOM 
    },
    _templates: {
       dropDown: "?"
    }
   });
   ui.plugin(Editable);
})(jQuery);

Answer 1

Following the blog you linked, simply do what he did - define your templates then create the drop-downs in your _create() function. It is not necessary to use the kendo.template() function on each drop down list, as it does not bind objects as well as you think it would. Instead, the key is to use kendo.bind() and pass in the options as your view model.

Here is a JsBin working example.

// listen for doc ready because this is js bin and my code is not really "in" the HTML
// where I can control it.
$(function() {
  // wrap the widget in a closure. Not necessary in doc ready, but a good practice
  (function($) { 
    var kendo = window.kendo,
        ui = kendo.ui,
        Widget = ui.Widget,
        periods = [{ text: "PERIOD: YEAR", value: "YEAR" }, { text: "PERIOD: QUARTER", value: "QUARTER" }],
        quarters = [{ text: "1. Quarter", value: 1 }, { text: "2. Quarter", value: 2 }, { text: "3. Quarter", value: 3 }, { text: "4. Quarter", value: 4 }],
        years = [2011, 2012, 2013, 2014];

    var LinkedDropDowns = Widget.extend({
      init: function(element, options) {
        var that = this;
        Widget.fn.init.call(that, element, options);      
        that._create();
      },
      options: {
        name: "LinkedDropDowns",
        period: "YEAR",
        periods: periods,
        year: 2011,
        years: years,
        yearVisible: true,
        quarter: 1,
        quarters: quarters,
        quarterVisible: false,
        onPeriodChange: function(e) {
          switch(e.sender.value()) {
            case "YEAR":
              this.set("yearVisible", true);
              this.set("quarterVisible", false);
              break;
            case "QUARTER":
              this.set("yearVisible", true);
              this.set("quarterVisible", true);
              break;
            default:
              break;
          }
        },
        onYearChange: function(e) {
          alert(e.sender.value());
        },
        onQuarterChange: function(e) {
          alert(e.sender.value());
        }
      },
      _create: function() {
        var that = this;

        // create dropdowns from templates and append them to DOM
        that.periodDropDown = $(that._templates.periodDropDown);
        that.yearDropDown = $(that._templates.yearDropDown);
        that.quarterDropDown = $(that._templates.quarterDropDown);

        // append all elements to the DOM
        that.element.append(that.periodDropDown)
                    .append(that.yearDropDown)
                    .append(that.quarterDropDown);

        kendo.bind(that.element, that.options);
      },
      _templates: {
        periodDropDown: "<input id='period' data-role='dropdownlist' data-text-field='text' data-value-field='value' data-bind='value: period, source: periods, events: { change: onPeriodChange }' />",
        yearDropDown: "<input id='year' data-role='dropdownlist' data-bind='visible: yearVisible, value: year, source: years, events: { change: onYearChange }' style='width: 90px' />",
        quarterDropDown: "<input id='quarter' data-role='dropdownlist' data-text-field='text' data-value-field='value' data-bind='visible: quarterVisible, value: quarter, source: quarters, events: { change: onQuarterChange }' style='width: 110px' />"
      }
    });

    ui.plugin(LinkedDropDowns);
  })(jQuery);

  $('#dropdowns').kendoLinkedDropDowns();
});