ExtJS: Show/hide control on checkbox selectionchange - checkbox

Question

I have an ExtJS check-tree ExtJS Check Tree that I am trying to add some control to based on items checked/unchecked. It doesn't seem to fire correctly though.
Here is a Fiddle Example
When checkbox 'A' is selected, I want to hide the textfield, 'testValue', which works, but then if I unselect checkbox 'A', I want to show the textfield, 'testValue', which does not work.
For this test I am merely looking to see if the selections.selected.length === 0. However, when I unselect any of the checkboxes, the listener does not seem to be firing, since the alert message is not getting triggered - plus, if I then try to reselect the check box again it still does not fire.
I would use a selection Model (as outlined below) to achieve this (since I know it works), but then this places checkboxes on all my tree items when I just want to have the leaf nodes with checkboxes.
selModel: {
type: 'checkboxmodel',
listeners: {
selectionchange: 'onCheckedNodesChange'
}
}
Any suggestions would be most welcome!
EDIT
Adding allowDeselect: true and a listener for select and deselect sort of worked (I updated the Fiddle to exhibit the behavior):
selModel: {
allowDeselect: true,
listeners: {
deselect: function(model, record, index) {
text = record.get('text');
alert(text);
},
select: function(model, record, index) {
text = record.get('text');
alert(text);
}
}
},
I want to make sure that when 'A' is selected, the textfield remains hidden, but if you select another item in the list and then deselect it, the textfield returns.
I am trying to use the getChecked() method alone with when selectionchange event occurs. However, this only seems to return data when I do a submit (for example, on the Get checked nodes control). Any suggestions would be most welcome. This should not be so difficult.

Answer 1

For tree panel we have checkchange event it is similar to the selectionchange event.
http://docs.sencha.com/extjs/4.2.5/#!/api/Ext.tree.Panel-event-checkchange
checkchange( node, checked, eOpts )
Fires when a node with a checkbox's checked property changes
Parameters
node : Ext.data.TreeModel
The node who's checked property was changed.
checked : Boolean
The node's new checked state
eOpts : Object
The options object passed to Ext.util.Observable.addListener.
var fields = [
{
name: 'column'
},
{
name: 'leaf',
type: 'boolean'
},
{
name: 'checked',
type: 'boolean'
},
{
name: 'cls',
type: 'string',
defaultValue: 'x-tree-noicon'
},
];
this.dataModel = Ext.define('Filter-' + this.getId(), {
extend: 'Ext.data.Model',
fields: fields,
});
columns: [
{
xtype: 'treecolumn',
width: 200,
itemId: "filter",
dataIndex: 'column' ,
renderer: function (val, metaData, r) {
},
scope: this,
},
],
listeners: {
'checkchange': Ext.bind(function (node, checked,eOpts) {
},
scope: this

Answer 2

The checkboxes you are seeing are not part of the selection behaviour. Instead, they come from the checked configuration on the NodeInterface class.
Your tree panel is using the default selModel, which is row-based selection, with no deselect option. If you want the in-tree checks to control the selection, you'll need to configure that manually, probably by listening to change events from the store.
OTH, if all you care about is finding out which items are checked or not, you can use the getChecked() method on the TreePanel