second dojo FilteringSelect control onChange event doesn't get fired

Question 1

bishop, thanks for your answer, I think I wasn't clear with my question, I do understand that the "onChange" event is supposed to get fired when the user (or something in the background) changes the selected item in the FilteringSelect, so my problem was that when the user selects an item from the second FilteringSelect control its onchange event didn't get fired.

As you suggested I tryed a simpler example (with a hard coded Memory objects) and it did work, so I started to dig a little bit more and realized that the problem was with my memory object,

Aparently when you declare a Memory object you have to make sure that there is an ID filed in the array collection objects, like in the next example:

var stateStore = new Memory({
            data: [
                {name:"Alabama" id:"AL"},
                {name:"Alaska", id:"AK"},
                {name:"American Samoa", id:"AS"},
                {name:"Arizona", id:"AZ"},
                {name:"Arkansas", id:"AR"},
                {name:"Armed Forces Europe", id:"AE"},
                {name:"Armed Forces Pacific", id:"AP"},
                {name:"Armed Forces the Americas", id:"AA"},
                {name:"California", id:"CA"},
                {name:"Colorado", id:"CO"},
                {name:"Connecticut", id:"CT"},
                {name:"Delaware", id:"DE"}
            ]
        });
        this.fieldDijit.set('store', stateStore);

When you don't explicitly tell it in the memory object declaration, it is asummed that there is a field called "id". In my case, the array that I assing to the memory object in the second filteringSelect didn't have a field called "id"

so I changed:

var fieldsStore = new Memory({
            data: layerInfo.fields
        });

for:

var fieldsStore = new Memory({
            idProperty: "name", //added this
            data: layerInfo.fields
        });

and now the event gets fired when the selected item in the second filterin select changes.

Question 2

Based on what I'm reading, I think you're expecting this code:

this.fieldDijit.set('store', fieldsStore);

to cause the second select in your co-dependent select arrangement to fire its change event -- after all, the select has "changed" in the sense that it has a different store.

But that's not what the change event means. The change event means the user has changed the selected value. So after setting a new store, if you select a value in the second drop down, your change handler should fire.

Here's an example that I think reduces yours to its simplest elements. Notice how when you select the first box's value, the second's store changes but its onchange event does not fire (as expected). But when you select the second box's value, its onchange does fire (as expected):

<!DOCTYPE html>
<html>
    <head>
        <link href='//ajax.googleapis.com/ajax/libs/dojo/1.9.1/dijit/themes/claro/claro.css' rel='stylesheet' type='text/css' />
        <script src='//ajax.googleapis.com/ajax/libs/dojo/1.9.1/dojo/dojo.js'></script>
    </head>
    <body class='claro'>
        <div data-dojo-id='s1' data-dojo-type='dojo/store/Memory' data-dojo-props='data:[{id:1,name:"A"}]'></div>
        <div data-dojo-id='s2' data-dojo-type='dojo/store/Memory' data-dojo-props='data:[{id:1,name:"C"}]'></div>
        <select data-dojo-id='first' data-dojo-type='dijit/form/ComboBox' data-dojo-props='store:s1'>
            <script type='dojo/method' event='onChange'>
                second.set('store', s2);
            </script>
        </select>

        <select data-dojo-id='second' data-dojo-type='dijit/form/ComboBox'>
            <script type='dojo/method' event='onChange'>
                alert('I am changed');
            </script>
        </select>

        <script type='text/javascript'>
        require(['dojo/ready', 'dojo/parser'], function (ready, Parser) {
            ready(function () {
                Parser.parse().then(function () {
                });
            });
        });
        </script>
    </body>
</html>

If I'm not understanding the error you're describing, can you send a simpler test case?