swt - Delete rows from Nattable

Question

I want to implement a row deletion logic in a Nebula Nattable. This is what I plan to do:

1. Add context menu to the Nattable which is described in http://blog.vogella.com/2015/02/03/nattable-context-menus-with-eclipse-menus/
2. Add an SWT Action to the menu which will implement the delete

my question is, which is the best way to accomplish this:

• Should I delete the corresponding value from my data model and the table view is refreshed when I execute this.natview.refresh();? OR
• Should I get the rows from SelectionLayer and delete them (if so how do I do ?)? OR
• is there any default support for this function through IConfiguration?

Answer 1

In NatTable you would typically do the following:

1. Create a command for deleting a row

   public class DeleteRowCommand extends AbstractRowCommand {
   
       public DeleteRowCommand(ILayer layer, int rowPosition) {
           super(layer, rowPosition);
       }
   
       protected DeleteRowCommand(DeleteRowCommand command) {
           super(command);
       }
   
       @Override
       public ILayerCommand cloneCommand() {
           return new DeleteRowCommand(this);
       }
   
   }
   

2. Create a command handler for that command

   public class DeleteRowCommandHandler<T> implements ILayerCommandHandler<DeleteRowCommand> {
   
       private List<T> bodyData;
   
       public DeleteRowCommandHandler(List<T> bodyData) {
           this.bodyData = bodyData;
       }
   
       @Override
       public Class<DeleteRowCommand> getCommandClass() {
           return DeleteRowCommand.class;
       }
   
       @Override
       public boolean doCommand(ILayer targetLayer, DeleteRowCommand command) {
           //convert the transported position to the target layer
           if (command.convertToTargetLayer(targetLayer)) {
               //remove the element
               this.bodyData.remove(command.getRowPosition());
               //fire the event to refresh
               targetLayer.fireLayerEvent(new RowDeleteEvent(targetLayer, command.getRowPosition()));
               return true;
           }
           return false;
       }
   
   }
   

3. Register the command handler to the body DataLayer

   bodyDataLayer.registerCommandHandler(
           new DeleteRowCommandHandler<your type>(bodyDataProvider.getList()));
   

4. Add a menu item to your menu configuration that fires the command

   new PopupMenuBuilder(natTable)
           .withMenuItemProvider(new IMenuItemProvider() {
   
               @Override
               public void addMenuItem(NatTable natTable, Menu popupMenu) {
                   MenuItem deleteRow = new MenuItem(popupMenu, SWT.PUSH);
                   deleteRow.setText("Delete");
                   deleteRow.setEnabled(true);
   
                   deleteRow.addSelectionListener(new SelectionAdapter() {
                       @Override
                       public void widgetSelected(SelectionEvent event) {
                           int rowPosition = MenuItemProviders.getNatEventData(event).getRowPosition();
                           natTable.doCommand(new DeleteRowCommand(natTable, rowPosition));
                       }
                   });
               }
           })
           .build();
   

Using this you don't need to call NatTable#refresh() because the command handler fires a RowDeleteEvent. I also don't suggest to call NatTable#refresh() in such a case, as it might change and refresh more than it should and would not update other states correctly, which is done correctly by firing the RowDeleteEvent.

Note that the shown example deletes the row for which the context menu is opened. If all selected rows should be deleted, you should create a command handler that knows the SelectionLayer and retrieve the selected rows as shown in the other answer.