com.smartgwt.client.widgets.tree.events

## Interface FolderDropHandler

- All Superinterfaces:
    EventHandler

      public interface FolderDropHandler
      extends EventHandler

- - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `onFolderDrop(FolderDropEvent event)` Process a drop of one or more nodes on a TreeGrid folder.

- - ### Method Detail

    - #### onFolderDrop

          void onFolderDrop(FolderDropEvent event)

      Process a drop of one or more nodes on a TreeGrid folder.

      This method can be overridden to provide custom drop behaviors and is a more appropriate override point than the lower level `Canvas.drop()` handler.

      If this is a self-drop, nodes are simply reordered. An "update" operation will be submitted to update the `parentId` field of the moved node(s).

      For a drop from another widget, `TreeGrid.transferDragData()` is called which, depending on the `dragDataAction` specified on the source widget, may either remove the source nodes from the original list (`dragDataAction:"move"`) or just provide a copy to this tree (`dragDataAction:"copy"`).

      In either case the new row(s) appear in the `folder` at the `index` specified by the arguments of the same name.

      If this grid is databound, the new nodes will be added to the dataset by calling `DataSource.addData()`. Further, if the new nodes were dragged from another databound component, and `addDropValues` is true, `getDropValues` will be called for every item being dropped.

      As a special case, if the `sourceWidget` is also databound and a `foreignKey` relationship is declared from the `sourceWidget`'s DataSource to this TreeGrid's DataSource, the interaction will be treated as a "drag recategorization" use case such as files being placed in folders, employees being assigned to teams, etc. "update" DSRequests will be submitted that change the foreignKey field in the dropped records to point to the tree folder that was the target of the drop. In this case no change will be made to the Tree data as such, only to the dropped records.

      For multi-record drops, Queuing is automatically used to combine all DSRequests into a single HTTP Request (see QuickStart Guide, Server Framework chapter). This allows the server to persist all changes caused by the drop in a single transaction (and this is automatically done when using the built-in server DataSources with Power Edition and above).

      If these default persistence behaviors are undesirable, Call `FolderDropEvent.cancel()` from within `onFolderDrop(com.smartgwt.client.widgets.tree.events.FolderDropEvent)` to cancel them, then and implement your own behavior, typically by using grid.updateData() or addData() to add new records.

      NOTE: the records you receive in this event are the actual Records from the source component. Use `DataSource.copyRecords()` to create a copy before modifying the records or using them with updateData() or addData().

      Parameters:
        `event` - the event