How to display sub categories

[pluto_44]

I have recently made an application where few categories are displayed. But I also want the sub categories to be displayed on clicking the parent categories menu. However I have used the following code to display the categories.
My store code is----

Ext.define('listdemo.store.Sections', {
extend : 'Ext.data.Store',


config : {
autoLoad: true,
model: 'listdemo.model.Sections',

proxy:{
type : 'ajax',
url:'http://localhost/catt.php',

reader:{
type:'json',
rootProperty:'categories'
}

}
}
});

The model code is----

Ext.define('listdemo.model.Sections', {
extend: 'Ext.data.Model',

config: {
fields: ['categories_id', 'categories_name','subcategories'],


}
});
And the view is-----

Ext.define('listdemo.view.Main',{
extend: 'Ext.NestedList',
xtype:'main',
requires: [
'Ext.TitleBar',
'Ext.dataview.List',
'Ext.data.Store',
'Ext.dataview.NestedList'
],

config:{
title: 'Categories',
//store:'Sections',
items:[
{
xtype:'list',
itemTpl:'{categories_name}',
title:'Categories',
store:'Sections',

}
]
}
});

I have a php file which returnes as follows----

{"categories":[{"categories_id":"1","categories_name":"Hardware","subcategories":[{"categories_id":"4","categories_name":"Graphics Cards"},{"categories_id":"5","categories_name":"Printers"},{"categories_id":"6","categories_name":"Monitors"},{"categories_id":"7","categories_name":"Speakers"},{"categories_id":"8","categories_name":"Keyboards"},{"categories_id":"9","categories_name":"Mice"},{"categories_id":"16","categories_name":"Memory"},{"categories_id":"17","categories_name":"CDROM Drives"}]},{"categories_id":"2","categories_name":"Software","subcategories":[{"categories_id":"18","categories_name":"Simulation"},{"categories_id":"19","categories_name":"Action"},{"categories_id":"20","categories_name":"Strategy"}]},{"categories_id":"3","categories_name":"DVD Movies","subcategories":[{"categories_id":"10","categories_name":"Action"},{"categories_id":"11","categories_name":"Science Fiction"},{"categories_id":"12","categories_name":"Comedy"},{"categories_id":"13","categories_name":"Cartoons"},{"categories_id":"14","categories_name":"Thriller"},{"categories_id":"15","categories_name":"Drama"}]}]}

Thanks in advance.....

[mitchellsimoens]

Why not use NestedList and TreeStore?