Extjs4 - remote validation

Question

I\'d like having a remote validator for a textfield. My PHP returns true/false value. I\'ve tried something like this:

{
   xtype: \'textfield\',
   fieldLabel:          


        

Answer 1

{
 fieldLabel : 'Username',
 name : 'username',
 allowBlank : false,
 validFlag : true,
 validator : function() {
  return this.validFlag;
 },
 listeners : {
  'change' : function(textfield, newValue, oldValue) {
   var me = this;
   Ext.Ajax.request({
    url : 'rest/users?action=validate&username=' + newValue,
    success : function(response) {
     // Ausuming responseText is {"valid" : true}
     me.validFlag = Ext.decode(response.responseText).valid ? true : 'The username is duplicated!';
     me.validate();
    }
   });
  }
 }
}

this html code i tested(extjs version is 5.0) ,is ok ,it is from TonyTuan'sBlog , all of this you can see this link : http://code.tonytuan.org/2013/06/extjs-remote-validator-for-form-field.html