Events of multiple cells in single column - gwt

Question

I have two buttons(edit + delete) in one column.
ButtonCell functionButtonCell = new ButtonCell() {
#Override
public void render(final Context context, final SafeHtml data, final SafeHtmlBuilder sb) {
sb.appendHtmlConstant("<button type='button' class='gwt-Button' style = 'width:60px;margin:1px;'>Edit</button>");
sb.appendHtmlConstant("<br/>");
sb.appendHtmlConstant("<button type='button' class='gwt-Button' style = 'width:60px;margin:1px;'>Delete</button>");
}
};
functionColumn = new Column<AdminModel, String>(functionButtonCell) {
public String getValue(final AdminModel object) {
return object.getSeq().toString();
}
};
Bind event for this column in Presenter as
.........
view.getFunctionColumn().setFieldUpdater(new FieldUpdater<AdminModel, String>() {
public void update(final int index, final AdminModel object, final String value) {
Window.alert(index + "-" + value);
}
});
After clicked on edit button , alert-box has appeared , but not on delete button. When I clicked on delete button , nothing has appeared. What would be the problem ?
Addition: How can I decide which button was clicked by user (edit or delete) from my presenter ?
I would really appreciate any of your suggestions because I am troubled on it for a long times. Thanks!

Answer 1

ButtonCell filters events on the first child element only: https://gwt.googlesource.com/gwt/+/2.6.1/user/src/com/google/gwt/cell/client/ButtonCell.java This is why you don't get an event when clicking the second button (note: the goal of that code is to make sure you clicked on the button, and not on blank space around the button; see https://gwt.googlesource.com/gwt/+/a0dc88c8be7408be9554f746eb1ec93798183a28)
The easiest way to implement a two-button cell is to use a CompositeCell; it requires that child cells are rendered into sibling elements though (uses <span>s by default, example below overrides the rendering to use <div>s so your buttons stack each on its own line).
new CompositeCell<AdminModel>(Arrays.asList(
// First button
new HasCell<AdminModel, String>() {
#Override public Cell<String> getCell() { return new ButtonCell(); }
#Override public FieldUpdated<AdminModel, String> getFieldUpdater() {
return new FieldUpdater<AdminModel, String>() {
#Override public void update(int index, AdminModel object, String value) {
Window.alert("Edit " + object.getId());
}
};
}
#Override public String getValue(AdminModel o) {
return "Edit";
}
},
// Second button
new HasCell<AdminModel, String>() {
#Override public Cell<String> getCell() { return new ButtonCell(); }
#Override public FieldUpdated<AdminModel, String> getFieldUpdater() {
return new FieldUpdater<AdminModel, String>() {
#Override public void update(int index, AdminModel object, String value) {
Window.alert("Delete " + object.getId());
}
};
}
#Override public String getValue(AdminModel o) {
return "Delete";
}
}) {
#Override protected <X> void render(Cell.Context context, AdminModel value, SafeHtmlBuilder sb, HasCell<String,X> hasCell) {
// use a <div> instead of the default <span>
Cell<X> cell = hasCell.getCell();
sb.appendHtmlConstant("<div>");
cell.render(context, hasCell.getValue(value), sb);
sb.appendHtmlConstant("</div>");
}
};
(note: in your case, because the button's text doesn't depend on the row object, maybe you should rather use an ActionCell; it would better fit "semantically" with what you're doing, but otherwise it's almost the same; with an ActionCell, you'd use HasCell<AdminModel, AdminModel>, ActionCell<AdminModel>, getFieldUpdater would return null, and thegetValueof theHasCellwould just return theAdminModel` argument as-is).
Otherwise, implement your Cell (or AbstractCell) entirely by yourself.

Answer 2

Ideally, a column should have only one type of cell be it ImageCell, ButtonCell etc. Because all this ImageCell and ButtonCell does not provide any in-built events. The events are handled by FieldUpdater itself which does not have differentiators to identify that which ButtonCell is clicked. Ideally on click of that column, the field-updater will be called.
You should rather create your own composite widget which extends HasCell. This composite widget will have two different buttons and those in built methods are called on click of respective button.
public void onModuleLoad() {
CellTable<Person> table = new CellTable<Person>();
List<HasCell<Person, ?>> cells = new LinkedList<HasCell<Person, ?>>();
cells.add(new ActionHasCell("Edit", new Delegate<Person>() {
#Override
public void execute(Person object) {
// EDIT CODE
}
}));
cells.add(new ActionHasCell("Delete", new Delegate<Person>() {
#Override
public void execute(Person object) {
// DELETE CODE
}
}));
CompositeCell<Person> cell = new CompositeCell<Person>(cells);
table.addColumn(new TextColumn<Person>() {
#Override
public String getValue(Person object) {
return object.getName()
}
}, "Name");
// ADD Cells for Age and Address
table.addColumn(new Column<Person, Person>(cell) {
#Override
public Person getValue(Person object) {
return object;
}
}, "Actions");
}
private class ActionHasCell implements HasCell<Person, Person> {
private ActionCell<Person> cell;
public ActionHasCell(String text, Delegate<Person> delegate) {
cell = new ActionCell<Person>(text, delegate);
}
#Override
public Cell<Person> getCell() {
return cell;
}
#Override
public FieldUpdater<Person, Person> getFieldUpdater() {
return null;
}
#Override
public Person getValue(Person object) {
return object;
}
}
Also, see the link below.
[GWT CellTable-Need to have two buttons in last single cell of each row