Listview with Checkbox is not responding based on the enable condition?

Question

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="Test.View.Test"
             Title="Test">
    <StackLayout>
        <Border StrokeThickness="2" HeightRequest="320" WidthRequest="200">
            <ListView ItemsSource="{Binding Items}"  HeightRequest="320" WidthRequest="200">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <ViewCell>
                        <StackLayout Orientation="Horizontal" Padding="10">
                                <CheckBox IsChecked="{Binding IsChecked}" VerticalOptions="Center" CheckedChanged="CheckBox_CheckedChanged" IsEnabled="{Binding IsEnabled}" />
                                <Label Text="{Binding Name}" VerticalOptions="Center" Margin="10,0,0,0" IsEnabled="{Binding IsEnabled}" />
                        </StackLayout>
                    </ViewCell>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>
        </Border>
    </StackLayout>
    
</ContentPage>

public partial class Test : ContentPage
{
    Testviewmodel _viewmodel = new Testviewmodel();
    public Test()
	{
		InitializeComponent();
        this.BindingContext = _viewmodel;

}

    private void CheckBox_CheckedChanged(object sender, CheckedChangedEventArgs e)
    {
        try
        {
            if (_viewmodel.Flag)
            {
                foreach (var item in _viewmodel.Items)
                {
                    if(e.Value)
                    {
                        if (item.IsChecked == true)
                        {

                            item.IsEnabled = true;
                        }
                        else
                        {
                            item.IsEnabled = false;
                        }

                    }
                    else
                    {
                        item.IsChecked = false;
                        item.IsEnabled = true;
                    }
                    

                }
                _viewmodel.Flag = false;
                _viewmodel.Items = new ObservableCollection<ITEMTEST>(_viewmodel.Items);
                _viewmodel.Flag = true;
            }
        }
        catch (Exception ex)
        {

        }
    }
}

public partial class Testviewmodel: ObservableObject
{

    [ObservableProperty]
    ObservableCollection<ITEMTEST> items;

    [ObservableProperty]
    bool flag = true;
    public Testviewmodel()
    {
        Items = new ObservableCollection<ITEMTEST>
    {
        new ITEMTEST { Name = "ITEMTEST 1" ,IsChecked = false, IsEnabled = true },
        new ITEMTEST { Name = "ITEMTEST 2" ,IsChecked = false, IsEnabled = true},
        new ITEMTEST { Name = "ITEMTEST 3" ,IsChecked = false, IsEnabled = true},
        new ITEMTEST { Name = "ITEMTEST 4" ,IsChecked = false, IsEnabled = true},
        new ITEMTEST { Name = "ITEMTEST 5" ,IsChecked = false, IsEnabled = true},
        new ITEMTEST { Name = "ITEMTEST 6" ,IsChecked = false, IsEnabled = true},
        new ITEMTEST { Name = "ITEMTEST 7" ,IsChecked = false, IsEnabled = true},
        new ITEMTEST { Name = "ITEMTEST 8" ,IsChecked = false, IsEnabled = true},
        new ITEMTEST { Name = "ITEMTEST 9" ,IsChecked = false, IsEnabled = true},
        new ITEMTEST { Name = "ITEMTEST 10" ,IsChecked = false, IsEnabled = true}
    };
    }
}

Expectation : Only One should be allowed to tick.
If the user want to change then they have to untick the already ticked one and re-tick it on the required item.

Issue:

For the first 5 visible items there is no issue . But if the user scroll and try to tick from 6 to 10 item.
It is not working as i expect.

Answer 1

Hello,

Please remove following lines in your CheckBox_CheckedChanged event.

    _viewmodel.Flag = false;
    _viewmodel.Items = new ObservableCollection<ITEMTEST>(_viewmodel.Items);
    _viewmodel.Flag = true;

And make sure your properties added the [ObservableProperty] in ITEMTEST.cs like following code.

public partial class ITEMTEST : ObservableObject
{
    [ObservableProperty]
    string name;
 
    [ObservableProperty]
    bool isChecked;
 
    [ObservableProperty]
    bool isEnabled;
}

If so, your properties could be changed at runtime, no need to set _viewmodel.Items = new ObservableCollection<ITEMTEST>(_viewmodel.Items); again.

By the way, ObservableCollection have implement the INotifyCollectionChanged as well.

Best Regards,

Leon Lu

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