My colNames and colModel change upon each paging. If you wonder why, it is because the grid data comes from dynamic crosstab, so I never know in advance how many columns I will have.  

I do know the maximum number of columns I can have.

So, here is what I am doing: Get all possible column names into colNames (and colModel) and feed it to my jqGrid.

In loadComplete (or gridComplete), I code to hide those columns that do not contain data.

Then in onPaging, I code to show all colNames.

This works Okay. 

But, if would be nicer if I can re-assign colNames and colModel to jqGrid upon paging, something like this:

1.  onPaging: function (pgButton) {
            //$.ajax call to get colNames and colModel and assign them to this current jqGrid
      }

Is there anyway to do this with jqGrid?