How to create CellTree with MVP pattern - gwt

Question

As suggested in gwt documentation, I try to follow the MVP design pattern while creating my application. When using simple tree, the example in the documentation is straight forwards and makes good example of MVP and gwt. In the example the view is created and the data is given to the view to display. As far as I understand this is exactly the way to keep view, model and presenter separated.
With CellTree, the data populating happens inside the TreeViewModel's data provider. Data provider cannot be taken outside the cell tree and therefore I need to do all data populating inside the cell tree, which is in the view. Now, the view needs to know about the model and the MVP patter is broken. I wan't to dynamically populate data to the cell tree prior to showing it to user, I need to edit the data in cell tree and save it later for different format.
My question goes how to implement CellTree, or in general Cell widgets, in MVP design patter?

Answer 1

I have used CellTable with MVP.
UI:
<g:HTMLPanel>
<g:ScrollPanel>
<p1:CellTable ui:field="cellTable" width="100%" styleName="style.cellTable" height="100%" />
</g:ScrollPanel>
</g:HTMLPanel>
View Interface:
public interface SomeCellListView extends IsWidget {
void setPresenter(Presenter listener);
// Method to set the CellTable data
void setCellList(ArrayList<ObjectDTO> list);
public interface Presenter {
void goTo(Place place);
void doSomething(int id);
}
}
View Implementation:
public class SomeCellListViewImpl extends Composite implements SomeCellListView {
... all Ui Binder stuff here
#UiField(provided = true)
CellTable<ObjectDTO>cellTable = new CellTable<ObjectDTO>();
SomeCellListViewImpl(){
TextColumn<ObjectDTO> someColumn= new TextColumn<ObjectDTO>(){
#Override
public String getValue(ObjectDTO o) {
return o.getSomeFieldValue();
}
};
cellTable.addColumn(someColumn, "column1");
... add other columns here
}
// This method is called from Presenter to set CellTable data
public void setCellList(ArrayList<ObjectDTO> list) {
cellTable.setRowCount(list.size(), true);
cellTable.setRowData(0, list);
}
}
Activity (or Presenter):
// Set view and service in the constructor (Get the view from ClientFactory)
public void start(AcceptsOneWidget containerWidget, EventBus eventBus) {
// Make RPC call
this.service
.getCellList(new AsyncCallback<ArrayList<ObjectDTO>>(){
#Override
public void onFailure(Throwable caught) {
view.setError("Error fetching details");
}
#Override
public void onSuccess(ArArrayList<ObjectDTO> result) {
view.setCelllist(result);
}
});
view.setPresenter(this);
containerWidget.setWidget(view.asWidget());
}
Here, the view is already created by ClientFactory. View contains just the layout for CellTable. Data is not loaded when view is created. When an Activity is started (aka Presenter), the "start" method is invoked. Here we make the RPC to get Cell data and call a method in the view to set the data.
I've not used CellTree. But you asked in general about Cell widgets. Hence thought of sharing this. Hope this helps.

Answer 2

i have the same issue with OP. I read the MVP tutorial part II, and then try to use CellTable in my application, while still keep the MVP architect. But i confuse at the part: the tutorial use the syntax like Presenter, but why you only use Presenter ?