DataTemplate bindings do not work

[AlphaNERD-]

Description

Helllo again .NET MAUI dev team,

i have discovered another issue with bindings in .NET MAUI: When trying to bind to a property within a DataTemplate, i do not get the value of the property i bound to. Instead i get the ToString() output of the object whose property i wanted to make a binding to.

I've created a WPF version of this demo project to ensure that i created the bindings correctly: https://github.com/AlphaNERD-/WPFBindingDemo/

Steps to Reproduce

1. Build the project for Android (See issue Invoking the PropertyChanged event throws NullReferenceException #21431 for the reason why)
2. Enter something within the entry. Ideally one of the first or last names listed within the constructor of ViewModelTest

Expected result:
You should see a list of names appear under the entry.

Actual result:
You see a list of "BindingDemoForGithub.ViewModelTest+TestUser" appear under the entry.

Link to public reproduction project repository

https://github.com/AlphaNERD-/NETMAUIBindingDemo

Version with bug

8.0.7 SR2

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

Android, I was not able test on other platforms

Affected platform versions

Android 14

Did you find any workaround?

One way we could get around this is to use ToString(). This will help users working with VERY simple lists.

Relevant log output

No response

[mattleibow]

I think this is because ListView actually needs to use a ViewCell:

<ListView ItemsSource="{Binding TestUsers, Mode=TwoWay}">
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <Label Text="{Binding UserName}"/>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

Maybe this is a result of the sample app... But, another thing I notice is that you have a list view in a vertical stack and that is in a scroll view. Doing this will cause the entire list to load all views - which will disable virtualization. You probably need to use a Grid and do not put a virtualized control (listview/collection view) in a infinite control - stack layout and scroll view. Nested scrolling controls in the same direction effectively loads all views at startup.

[AlphaNERD-]

Adding the <ViewCell> tags fixed the binding issue. I do wonder though: Why do i need to use the <ViewCell> tags in the first place?

[jfversluis]

@AlphaNERD- that is the way it was setup for a ListView, all cells have to inherit from ViewCell also see the docs, this was changed for CollectionView.

Glad you got this to work!