ListView Selection does not work in Android

[markinnh]

I have a test app and I have been unable to get ListView Selection to work in Android. I am adding the ListView Xaml, maybe there is something missing for Android that I don't know about. I am running the latest release in Visual Studio 2022 17.4 Preview 2 and recently installed the Uno Templates (6/16), I have not installed any other extensions.

<ListView Name="BrowseInv" Grid.Row="2"  ItemsSource="{x:Bind CollectionView.View}" ItemTemplate="{StaticResource DisplayItem}" 
                  SelectionChanged="BrowseInv_Changed" VerticalAlignment="Stretch" 
                              Width="230"
                              SelectedItem="{x:Bind SelectedItem}">
                        <ListView.ItemsPanel>
                            <ItemsPanelTemplate>
                                <ItemsWrapGrid MaximumRowsOrColumns="2" Orientation="Horizontal"/>
                            </ItemsPanelTemplate>
                        </ListView.ItemsPanel>
                        <ListView.GroupStyle>
                            <GroupStyle HeaderTemplate="{StaticResource DisplayHeader}"/>
                        </ListView.GroupStyle>
                    </ListView>

[jeromelaban]

Thanks for the report.

It's likely that the issue you're seeing is related to the use of x:Bind and its default mode of OneTime. You can try with SelectedItem="{x:Bind SelectedItem, Mode=TwoWay}" and see if it helps.

Otherwise, you can try to see if this works on UWP or WinUI and let us know.

[markinnh]

It does work on WinUI3, no problem, but I have the SelectionChanged event hooked to a handler and nothing happens in Android. Also, I set up a project with the same XAML in UWP and it works in UWP but not in Android.

[jeromelaban]

Thanks. Could you create a repro project which shows what you're experiencing?

[markinnh]

This is the shared application, the entire project zipped is 200 Mb, so I can't do that. All my code (XAML/C#) is in these files. It does work in UWP/WinUI3, but fails when I try to run it on Android. Thanks, Mark

…

________________________________ From: Jérôme Laban ***@***.***> Sent: Sunday, June 19, 2022 9:26 PM To: unoplatform/uno ***@***.***> Cc: Mark Gillespie ***@***.***>; Author ***@***.***> Subject: Re: [unoplatform/uno] ListView Selection does not work in Android (Discussion #9076) Thanks. Could you create a repro project which shows what you're experiencing? — Reply to this email directly, view it on GitHub<https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Funoplatform%2Funo%2Fdiscussions%2F9076%23discussioncomment-2982170&data=05%7C01%7C%7C69794cb9134140c760ce08da525be778%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637912851923272535%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=ycZbQWXJPTEjk6wApvwyLI9d61AhkGgwbAohKw8Jrzk%3D&reserved=0>, or unsubscribe<https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fnotifications%2Funsubscribe-auth%2FAHYFJJFOPEJYMOBJBM7LF7LVP7CELANCNFSM5ZGWZTCA&data=05%7C01%7C%7C69794cb9134140c760ce08da525be778%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637912851923272535%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=W7rgX8R7BItiN1FxFGcLaAnKFbeiZzj7tWU3t0lwNIM%3D&reserved=0>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[jeromelaban]

If you want to zip the project, you can remove all the bin and obj folders.

[markinnh]

I removed all the bin and obj files, the project is zipped
UnoTestApp2.zip
.

[markinnh]

Found the problem, can't use CollectionViewSource.

[jeromelaban]

Thanks for the update. It's likely that we have an issue in CollectionViewSource, it's supposed to be supported properly.

[jeromelaban]

The issue you've faced here is #7494, where it's generally best to avoid providing a lazy enumerable to collections for performance reasons, even on WinUI/UWP.

If you use .ToArray() at the end, the behavior is the right one:

        public IEnumerable<IGrouping<int, Item>> GroupedItems => (from item in GetItems()
                                                                 group item by item.GroupId into g
                                                                 orderby g.Key
                                                                 select g).ToArray();

In all cases, it's best to expose an ObservableCollection<> instead, as it is built to handle updates properly, instead of relying on eventual binding refresh.