I dont want to have to define the order of the columns in the data service. I think that it is better that the grid determines the order of columns. Because I cannot seem to figure out how to get jqGrid to do this I have decided to use the 'postData' attribute to pass back a list of columns in the order that I want. The service then uses this list to sort the columns. Its not the optimum way to do it but its better than hardcoding the column order in the service itself.
If there is some other way to achieve this I would like to know.