GWT CellTable/DataGrid - how to detect column selection?

Question

When a row is selected, I would like to know which column of that row was selected.

Currently, I would override onBrowserEvent2

protected void onBrowserEvent2(Event event)
{
  // Get the event target.
  EventTarget eventTarget = event.getEventTarget();
  if (!Element.is(eventTarget)){
    return;
  }

  final Element target = event.getEventTarget().cast();

  // Find the cell where the event occurred.
  TableCellElement tableCell = findNearestParentCell(target);
  if (tableCell == null) {
    return;
  }

  int col = tableCell.getCellIndex();

  .... blah ... blah ....
}

where,

//exact replica code from {@link AbstractCellTable} private method findNearestParentCell
private TableCellElement findNearestParentCell(Element elem) {
  while ((elem != null) && (elem != getElement())) {
    // TODO: We need is() implementations in all Element subclasses.
    // This would allow us to use TableCellElement.is() -- much cleaner.
    String tagName = elem.getTagName();
    if ("td".equalsIgnoreCase(tagName) || "th".equalsIgnoreCase(tagName)) {
      return elem.cast();
    }
    elem = elem.getParentElement();
  }
  return null;
}

Is this the only way? Is there a selection model with a change event that would tell me which column of the row was clicked.

Is there a way to implement a click handler on a column or the cell of the column?

score 4 · Accepted Answer · answered Dec 19 '11 at 19:44

OMG ... this was a really simple solution.

Use an extension of ClickableTextCell for the column.

public class SelectableTextCell
extends ClickableTextCell
{
  @Override
  public void onBrowserEvent(
    Context context,
    Element parent,
    String value,
    NativeEvent event,
    ValueUpdater<String> valueUpdater)
  {
    GWT.log("event="+event.getType()); //$NON-NLS-1$
    doYourThing();
    if (IWishToPropagateTheClick)
      super.onBrowserEvent(context, parent, value, event, valueUpdater);
  }
}

Or for a more general case, extend AbstractCell, and specify the consumed events at the constructor.

Perhaps it's worth noting that in the above example you can reference context.getColumn(), which will return the column index of your cell. — Boris Brudnoy, Dec 20 '11 at 00:50

GWT CellTable/DataGrid - how to detect column selection?

1 Answers1