com.smartgwt.client.widgets.grid.events

## Interface GroupByHandler

- All Superinterfaces:
    com.google.gwt.event.shared.EventHandler

      public interface GroupByHandler
      extends com.google.gwt.event.shared.EventHandler

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `onGroupBy(GroupByEvent event)` Callback fired when the user attempts to group or ungroup the listGrid, or when `groupBy()` is called programmatically.

- - ### Method Detail

    - #### onGroupBy

          void onGroupBy(GroupByEvent event)

      Callback fired when the user attempts to group or ungroup the listGrid, or when `groupBy()` is called programmatically. This event may be cancelled.

      This notification is fired before the `data` is updated to reflect the grouping. See also `ListGrid.groupByComplete()`.

      Note that this method is not called when the data is regrouped, either `programmatically`, or in response to new data arriving from the server, and such regrouping can't be canceled - instead use callback `ListGrid.regroup()`.

      Parameters:
        `event` - the event