title: Refresh extjs form's submit data
body: <p>I have an extjs form (GET method) where some fields can be dynamically added or removed. i have also added a logic that changes names of fields for example</p>
  
  <pre><code>....
  items: [
           {
             xtype: 'textfield',
             fieldLabel: 'Username',
             name: 'data[param1][0]'
           },{
  ....
  </code></pre>
  
  <p>becomes</p>
  
  <pre><code>....
  items: [
           {
             xtype: 'textfield',
             fieldLabel: 'Username',
             name: 'data[param1][1]'
           },{
  ....
  </code></pre>
  
  <p>After I submit the form old data is submitted without any effect on added/removed fields or field name changes</p>
  
  <p>How to update or refresh form so it send correct. </p>
  
  <p><strong>EDIT</strong>
  Everything else is working correctly in this form for example form.load() loads the data from server side json and i can edit/save them back to db. when i use form.add(fields) method new fields are included in submit request but not delete. I read that EXJS form submit url data is calculated one time and other time when possibly some events are triggered.</p>
  
  <p>Main trouble is renaming the fields does not reflect submit data, i have checked manually by looking source that field names are changed properly from my logic. I call form.doLayout() after making changes in fields</p>