How to handle Datagrid column's events from Presenter?

Question

I am using GWT MVP and I would like to handle events in columns of DataGrid from Presenter. From GWT DataGrid ShowCase ...

    // First name.
Column<ContactInfo, String> firstNameColumn =
    new Column<ContactInfo, String>(new EditTextCell()) {
      @Override
      public String getValue(ContactInfo object) {
        return object.getFirstName();
      }
    };
firstNameColumn.setSortable(true);
sortHandler.setComparator(firstNameColumn, new Comparator<ContactInfo>() {
  @Override
  public int compare(ContactInfo o1, ContactInfo o2) {
    return o1.getFirstName().compareTo(o2.getFirstName());
  }
});
dataGrid.addColumn(firstNameColumn, constants.cwDataGridColumnFirstName());
firstNameColumn.setFieldUpdater(new FieldUpdater<ContactInfo, String>() {
  @Override
  public void update(int index, ContactInfo object, String value) {
    // Here I would like to call RPC methods
  }
});
dataGrid.setColumnWidth(firstNameColumn, 20, Unit.PCT);

Above example , this code is writing in View side and it just really example. As mvp pattern , I just need to call rpc request to update database. This can't be done in View side but I have no idea how to set FieldUpdater from my presenter. Please help me how can I figure it out ? Thanks greatly .

Answer 1

There are two ways to do this (MVP I or MVP II way):

MVP 1 style:

http://www.gwtproject.org/articles/mvp-architecture.html

Create a setter on your View (i.e. setFieldUpdater(FieldUpdater<ContactInfo, String>)) that takes a FieldUpdater and adds it to the column. From the Presenter you can call (provided that view is the reference to your View).

Presenter:

view.setFieldUpdater(new FieldUpdater<ContactInfo, String>() {
  @Override
  public void update(int index, ContactInfo object, String value) {
    // Make the RPC call
  }
});

MVP2 style:

http://www.gwtproject.org/articles/mvp-architecture-2.html

If you have a reference from your View back to your Presenter. Then you can call a function on your Presenter.

View:

firstNameColumn.setFieldUpdater(new FieldUpdater<ContactInfo, String>() {
  @Override
  public void update(int index, ContactInfo object, String value) {
    getPresenter().onUpdate(info,value);
  }
});