Combining AbstractBackEndDataProvider and Hierachial Behaviour

Vaadin 6 / 7 / 8 Framework Data Binding
1

The Model: Two Levels Author with (one:many) Books
What i try to acheive is to fetch lazy from backend when user scrolls. This works like a charm
with my FilterablePageableDataProvider< T extends AbstractDPSClient> extends AbstractBackEndDataProvider<Author, String>

Paging/sorting/filtering works just fine BUT for a flat structure.
I try to use the AbstractBackEndHierarchicalDataProvider but the design for this seems to be to only fetch Children Lazily, i have
the opposite issue. The Children already exists on the parents BUT i want to page fetch as user scrolls.

The
Stream fetchFromBackEnd(Query<Author, String> query);

Does not exist on the AbstractBackEndHierarchicalDataProvider only 

**Stream<DisplayVersion> fetchChildren(HierarchicalQuery<DisplayVersion, String> hierarchicalQuery)**


And that seems to be designed to lazyLoad children only?

How can i combine the behaviors?

I implemeted an inMemory solution using TreeData and TreeDataProvider but inMemory is not plausable for us.

How can i achieve this?

2

Yes, there are issues with lazyness with TreeGrid. We have one improvment under testing, you could check if it is somethign that could help you as well.

https://github.com/vaadin/framework/pull/10378

3

Ok

thanks i will take a look.

However it might be more than issues it seems that the design is based on the assumption that only
children needs to be lazyfetched when in fact i think most will use it for displaying pivoted data (
rather than oneRoot Trees) and hence it will be more important to lazyload parents than children,
best solution if both can be done and ideally optional.

This means that on FetchChildren there would be an easy way to let the provider get data from existing OR fetch.

Thanks again

Gerry