Databinding errors on ListView - What am I doing wrong?

[danielcooper-hk]

Hi everyone,

I am pulling what little hair I have left out over this - if someone can point me in the right direction I would be very grateful.

When the application runs there are no binding errors but when I click on the button to run the AddItemCommand the item appears in the list view but I get data binding errors on both Name and Description. What am I doing wrong in the ListView to cause this?

Thanks,

Dan.

I've written the following sample:

My MainPageModel:

namespace ListViewMVVM.Models;

public class MainPageModel
{
    public string Name { get; set; } = string.Empty;

    public string Description { get; set; } = string.Empty;
}

My MainPageViewModel:

namespace ListViewMVVM.ViewModels;

public class MainPageViewModel 
{
    public ICommand AddItemCommand { get; private set; }

    private ObservableCollection<MainPageModel> myItems;
    public ObservableCollection<MainPageModel> MyItems
    {
        get { return myItems; }
        set
        {
            if (myItems == value) return;

            myItems = value;
        }
    }

    public MainPageViewModel()
    {
        myItems = new()
        {
            new Models.MainPageModel { Name = "Item 1", Description = "Description 1" },
            new Models.MainPageModel { Name = "Item 2", Description = "Description 2" },
            new Models.MainPageModel { Name = "Item 3", Description = "Description 3" }
        };

        AddItemCommand = new Command(AddRecord);
    }

    public void AddRecord()
    {
        myItems.Add(new Models.MainPageModel
        {
            Name = "Item" + (myItems.Count + 1).ToString(), Description = "Description " + (myItems.Count + 1).ToString()
        }) ;

    }
}

My MainPage.xaml:

<?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"
             xmlns:viewmodels="clr-namespace:ListViewMVVM.ViewModels"
             xmlns:models="clr-namespace:ListViewMVVM.Models"
             x:Class="ListViewMVVM.MainPage">

   <ContentPage.BindingContext>
        <viewmodels:MainPageViewModel/>
    </ContentPage.BindingContext>
    
    <ScrollView>
        <VerticalStackLayout>

            <ListView x:Name="ListViewItems"
                      ItemsSource="{Binding MyItems}">
                <ListView.ItemTemplate>
                    <DataTemplate x:DataType="models:MainPageModel">
                        <TextCell Text="{Binding Name}"
                      Detail="{Binding Description}" />
                    </DataTemplate>
                </ListView.ItemTemplate>


            </ListView>

            <Button
                Text="Add Next"
                Command="{Binding AddItemCommand}"
                HorizontalOptions="Center" />

        </VerticalStackLayout>
    </ScrollView>

</ContentPage>

And finally the MainPage.xaml.cs:

namespace ListViewMVVM;

public partial class MainPage : ContentPage
{
	public MainPage()
	{
		InitializeComponent();
	}
}

[xtuzy]

maybe need delete x:DataType

[danielcooper-hk]

I did try that actually and its still the same. The list views are working fine but the binding errors are very annoying.

[xtuzy]

maybe you can ignore these error,add new item it work, so maybe is a bug of WinUI3 tool

[enjoysmath]

Having this same issue. Therefore their original issue has been verified by me. Please help us fix this issue! I don't want to go forward with my UI design which was kind of the only way left I could think of because CollectionView doesn't show anything... Here is the related SO post by me:

https://stackoverflow.com/q/77809597/7076615