Ext.grid.GridPanel and column sorting...

Tip: Do not use the field mapping option when enabling column sorting on a grid and just rely on the ColumnModel dataIndex to properly map property values from your source data. The reason being is the field name is passed on the sort parameter field value to the server and not the mapped property name. So if you do map a field, then you will have to manage the field name on the server side injecting display logic into your operations layer.