IndexOutOfBounds for DataProvider

Created a DataProvider.fromCallbacks object. First page of paging works correctly, second load of data,however causes an indexoutofbounds error: query.getOffset(): 0 query.getLimit(): 50 query.getOffset(): 50 query.getLimit(): 50 java.lang.IndexOutOfBoundsException: Index: 50, Size: 50

java.lang.IndexOutOfBoundsException: Index: 50, Size: 50 at java.util.ArrayList.rangeCheck(ArrayList.java:657) ~[na:1.8.0_212] at java.util.ArrayList.get(ArrayList.java:433) ~[na:1.8.0_212] at com.vaadin.flow.data.provider.DataCommunicator.lambda$getJsonItems$3(DataCommunicator.java:611) ~[flow-data-1.4.6.jar!/:1.4.6]

• Minimal reproducible example This is about as stripped down as I can make it quickly while keeping this verbose for you…

DataProvider<License,Void> licenseDataProvider = DataProvider.fromCallbacks(
                new CallbackDataProvider.FetchCallback<License, Void>() {
                    @Override
                    Stream<License> fetch(Query<License, Void> query) {
                        println "query.getOffset(): "+query.getOffset()
                        println "query.getLimit(): "+ query.getLimit()
                        Stream<License> licenseStream = licenseRepository.findByZenGroupId(user.getZenGroupId()).subList(query.getOffset(),query.getLimit()).stream()
                        //licensePage = licensePagingRepository.findAllByZenGroupId(user.getZenGroupId(), new PageRequest(query.getOffset(), limit))

                        return licenseStream
                    }
                },new CallbackDataProvider.CountCallback<License, Void>() {
            @Override
            int count(Query<License, Void> query) {
                //println "totalElements:"+licensePagingRepository.findAllByZenGroupId(user.getZenGroupId(), new PageRequest(query.getOffset(), query.getLimit())).getNumber()
                //println "numberOfElements:"+licensePagingRepository.countByZenGroupId(user.getZenGroupId(), new PageRequest(query.getOffset(), query.getLimit()))

                return licenseRepository.countByZenGroupId(user.getZenGroupId())
            }
        })

• Expected behavior DataProvider lazy loading population to a grid.
• Actual behavior Crash upon scroll.
• Versions:
  • Vaadin / Flow version 13.0.10
  • Java version Java: 1.8.212 zulu Spring: Spring boot 2.1.6.RELEASE
  • OS version: Server: Ubuntu
  • Browser version (if applicable) –N/A

[Legioth]

On a completely different note, I’d also like to address this comment:

It is out of scope, to provide you a fully functioning web application to demonstrate your method back to you. This is a unit testing issue on core Vaadin.

In order to determine that the problem was in the example code and not in Vaadin itself, I had to make assumptions about the implementation of the missing classes and how the data provider was used. This was a relatively straightforward case but as an example, the symptoms would have been different if I’d used the data provider with a Select component instead of Grid.

There have also been cases where we have made wrong assumptions without noticing and then ended up only implementing a partial fix or fixing a completely different related issue instead of fixing the issue faced by the reporter.

We are receiving hundreds of reports through open source issue trackers every week. We want to dedicate our time to fixing actual issues or implementing new features rather than filling in blanks in reported issues or making changes that are not helping the reporter. By providing a fully functional example that can be run as-is, you are significantly increasing the chances that you will receive help quickly and efficiently.

In this case, a functionally equivalent self-contained example could have been implemented like this:

@Route
public class Test extends Div {
    public Test() {
        List<String> items = IntStream.range(0, 500).mapToObj(Integer::toString)
                .collect(Collectors.toList());

        DataProvider<String, Void> licenseDataProvider = DataProvider
                .fromCallbacks(query -> {
                    Stream<String> licenseStream = items
                            .subList(query.getOffset(), query.getLimit())
                            .stream();
                    return licenseStream;
                }, query -> items.size());

        Grid<String> grid = new Grid<>();
        grid.setDataProvider(licenseDataProvider);
        grid.addColumn(item -> item);
        add(grid);
    }
}

[dennisunderwood]

@jhult I found a solution…we had moved on shortly afterwards.