Finally the solution was the following code in the gridComplete or loadComplete method:

 $("#jqGridTable").setGridParam({datatype:"local"})
                                                   .trigger("reloadGrid")
                                                   .setGridParam({datatype:"json"});

That was not exactly the solution I was looking because the jqGrid table fills two times the data on the table, the first one when gets de data from the server -addJSONData- and the second one when it is sorted locally.

I thought that jqGrid could sort the JSON data object before it is filled on the table, maybe in future versions.

Nevertheless, Tony your plugin it's great ... congratulations !!!.

Thanks and regards.

Ramón

Try to use gridComplete method where you can call sortData method - it is exactly what you want - do not use loadonce.

Regards

Tony

If I use loadonce:true de data only is obtained from the server once. 

I wanted that each time the user 'refresh' the table through the navigation bar or 'sorts' de data clicking a column header, jqGrid gets the server data through AJAX and sort it in client side BEFORE populating the rows on the table.  Is that possible?

Thanks and regards.

Ramón

Use loadonce:true - see docs

Regards

Tony

My table obtains and refresh the JSON data from the server - datatype: 'json' - but it can't be sorted on it.  I'd like that jqGrid before populating the server data on the table could sort it using the colModel criterias, the same way when the datatype is local.  Is that possible?.

Thanks in advance.

Ramón