title: Extjs - upload file using filefield
body: <p>My extjs code like <b><a href="http://www.objis.com/formationextjs/lib/extjs-4.0.0/docs/api/Ext.form.field.File.html">http://www.objis.com/formationextjs/lib/extjs-4.0.0/docs/api/Ext.form.field.File.html</a></b></p>
  
  <pre><code>Ext.create('Ext.form.Panel', {
      title: 'Upload a Photo',
      width: 400,
      bodyPadding: 10,
      frame: true,
      renderTo: Ext.getBody(),    
      items: [{
          xtype: 'filefield',
          name: 'photo',
          fieldLabel: 'Photo',
          labelWidth: 50,
          msgTarget: 'side',
          allowBlank: false,
          anchor: '100%',
          buttonText: 'Select Photo...'
      }],
  
      buttons: [{
          text: 'Upload',
          handler: function() {
              var form = this.up('form').getForm();
              if(form.isValid()){
                  form.submit({
                      url: 'photo-upload.php',
                      waitMsg: 'Uploading your photo...',
                      success: function(fp, o) {
                          Ext.Msg.alert('Success', 'Your photo "' + o.result.file + '" has been uploaded.');
                      }
                  });
              }
          }
      }]
  });
  </code></pre>
  
  <p>my photo-upload.php file</p>
  
  <pre><code>echo "{success:true}";
  </code></pre>
  
  <p>But when success <b>o.result.file</b> show <b>undefined</b>. I think it will show file name after success.
  <br>How can i make it show file name after success thanks</p>