How to enable/disable a forms button without Using Ext.getCmp() in extjs4?

Question

Here is the following form and i wanna access form`s apply button inside the form without using Ext.getCmp() and defining an id for the button:

{xtype : 'form',
url : 'index.php/submitform',
trackResetOnLoad : true,
id : 'generalprofilebasicinformation'+ this.getId(),
listeners : {
//is fired when the form is dirty(field values are modified)
    dirtychange : {
        fn : function(sm) {
    //Here Is my problem:
//How to  access to Apply button or any other buttons defined inside the form???
            var applyButton = this.Button;
   applyButton.enable();}}},
   buttons : [{
            text : 'Apply',
            formBind : true, // only
            // enabled
            // once the
            // form is
            // valid
            disabled : true,} ]}

Answer 1

You can use a controller to listen for the 'dirtychange' event fired by this form.

//controller init 
init: function() {
    this.control({
        'form': {
            dirtychange: function(form) {
                var button = form.owner.query('button[text=Apply]');
                button[0].enable();             
            }
        }
    });
}

The answer darren gave will certainly work, this just utilizes component queries to give you a different way to reach and control components. If you wanted to enable a series of buttons within the form, for example, you could remove the 'text=Apply' and an array of all the forms buttons will be returned.

Answer 2

Use a constructor and then you can create the button inside it and then have a reference to it in your form. Once you have the reference in the form, you can then retrieve it from the listener you have there. Would look like this:

contructor: function(config) {
   this.button = new Ext.Button({
       // Provide your button config here
   });
}

listeners: {
   dirtychange: function(sm) {
       this.button.enable();
   }
}

That should work without using Ext.getCmp()

Answer 3

Agreed with jthirau - definitely use component query.

Another way to do what you are doing is to simply add a button handler. This goes right on the button config:

handler:function(){
  //do something
}