When you filter Infragistics UltraWebGrid by clicking Filter icon in the column header – dropdown with filter values appears. Normally if you click elsewhere on the page – dropdown disappears. But sometimes it doesn’t, for example if you click an element that invokes a JavaScript function. Filter dropdown stays open and this could cause problems – when grid refreshes (and possibly other actions are performed) error is thrown:

‘this.Column.Band’ is null or not an object

The solution to this is to close filter dropdown ourselves. Put these lines into your client-side code whenever clicking outside the filter doesn’t close it:

var aGridCols = igtbl_getGridById('xMyGrid').Bands[0].Columns
   for (var I = 0; I < aGridCols.length; I++)
      aGridCols[I].showFilterDropDown(false);

Here we’re looping thru grids column collection (This example assumes grid is in Flat or OutlookGroupBy mode, if your grid is hierarchical, you will have to loop thru band collection as well). For every column we pass False to showFilterDropDown method which (probably showing Infragistics cute sense of humor) hides filter dropdown if it is open. If dropdown is hidden for the column already – nothing happens.

As a result opened filter dropdown is now always closed prior to previously offending action and the error doesn’t happen.