I'm using GWT 2.1's CellBrowser with a custom TreeViewModel. The TreeViewModel in turn uses an AsyncDataProvider to fetch data dynamically. This all works beautifully- when the user clicks on a node my AsyncDataProvider fetches the results via RPC, and the CellBrowser dutifully displays them.
I feel silly for not being able to figure this out, but how can I programmatically tell the CellBrowser to reload (and display) the data? I'm guessing that I need to somehow get a handle to the AsyncDataProvider for my root node and then call updateRowData() & updateRowCount() on it, but I don't see an obvious way to query the browser (or its model) for the root DataProvider.
I guess I could add code to my AsyncDataProvider constructor that looks for a null argument, and by that means recognize "hey, I'm the root" and store a reference somewhere, but that seems hackish. Surely there's a better way to do this.
Apologies for dumping so much code here, but I don't know how to boil this down to anything simpler and still provide enough context.
My AsyncDataProvider:
private static class CategoryDataProvider extends AsyncDataProvider<Category>
{
private Category selectedCategory;
private CategoryDataProvider(Category selectedCategory)
{
this.selectedCategory = selectedCategory;
}
@Override
protected void onRangeChanged(HasData<Category> display)
{
new AsyncCall<List<Category>>()
{
@Override
protected void callService(AsyncCallback<List<Category>> cb)
{
// default to root
String categoryId = "-1";
if (selectedCategory != null)
{
categoryId = selectedCategory.getCategoryId();
}
// when a category is clicked, fetch its child categories
service.getCategoriesForParent(categoryId, cb);
}
@Override
public void onSuccess(List<Category> result)
{
// update the display
updateRowCount(result.size(), true);
updateRowData(0, result);
}
}.go();
}
}
My model:
private static class CategoryTreeModel implements TreeViewModel
{
private SingleSelectionModel<Category> selectionModel;
public CategoryTreeModel(SingleSelectionModel<Category> selectionModel)
{
this.selectionModel = selectionModel;
}
/**
* @return the NodeInfo that provides the children of the specified category
*/
public <T> NodeInfo<?> getNodeInfo(T value)
{
CategoryDataProvider dataProvider = new CategoryDataProvider((Category) value);
// Return a node info that pairs the data with a cell.
return new TreeViewModel.DefaultNodeInfo<Category>(dataProvider, new CategoryCell(), selectionModel, null);
}
/**
* @return true if the specified category represents a leaf node
*/
public boolean isLeaf(Object value)
{
return value != null && ((Category) value).isLeafCategory();
}
}
And finally, here's how I'm using them:
CategoryTreeModel model = new CategoryTreeModel(selectionModel);
CellBrowser cellBrowser = new CellBrowser(model, null);