Datagrid ComboBox SelectedItem Show Error

[langsisi]

Describe the bug

// DataType ComboBox ItemsSource,this show OK
public static List DataTypes =>
Enum.GetNames(typeof(DataTypeEnum)).ToList();

// DataType2 ComboBox ItemsSource, no static ,this show Error
public List DataTypeList => Enum.GetNames(typeof(DataTypeEnum)).ToList();

To Reproduce

public enum DataTypeEnum
{
    Bit,
    Byte,
    Int16,
    Uint16,
    Int32,
    Uint32,
    Real,
    String,
    Wstring,
    DateTime
}

public partial class MainWindowViewModel : ViewModelBase
{
    [ObservableProperty]
    private ObservableCollection<TagViewModel>? _tags;

  // DataType ComboBox ItemsSource,this show OK
    public static List<string> DataTypes =>
  Enum.GetNames(typeof(DataTypeEnum)).ToList();

  // DataType2 ComboBox ItemsSource, no static ,this show Error
    public List<string> DataTypeList => Enum.GetNames(typeof(DataTypeEnum)).ToList();

    public MainWindowViewModel()
    {
        Tags = new ObservableCollection<TagViewModel>();
    }

    private static readonly Random _random = new Random();

    private string GenerateRandomAddress()
    {
        const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        return new string(Enumerable.Repeat(chars, 8)
          .Select(s => s[_random.Next(s.Length)]).ToArray());
    }

    [RelayCommand]
    private void Refresh()
    {
        var tags = new List<TagViewModel>
            {
                new TagViewModel { Id = 1, DeviceId = 101, DeviceName = "Device1", Name = "Tag1", Address = GenerateRandomAddress(), Desc = "Description1", DataType = DataTypeEnum.Int16.ToString(),DataType2=DataTypeEnum.Int16.ToString(), ArrayCount = 1 },
                new TagViewModel { Id = 2, DeviceId = 102,DataType2=DataTypeEnum.Int16.ToString(),  DeviceName = "Device2", Name = "Tag2", Address = GenerateRandomAddress(), Desc = "Description2", DataType = DataTypeEnum.Int32.ToString(), ArrayCount = 2 },
                new TagViewModel { Id = 3, DeviceId = 103, DeviceName = "Device3", Name = "Tag3", Address = GenerateRandomAddress(), Desc = "Description3", DataType = DataTypeEnum.Real.ToString(), DataType2=DataTypeEnum.Int16.ToString(), ArrayCount = 3 },
                new TagViewModel { Id = 4, DeviceId = 104, DeviceName = "Device4", Name = "Tag4", Address = GenerateRandomAddress(), Desc = "Description4", DataType = DataTypeEnum.String.ToString(), DataType2 = DataTypeEnum.Int16.ToString(), ArrayCount = 4 }
            };

        Tags?.Clear();
        foreach (var tag in tags)
        {
            Tags?.Add(tag);
        }

    }
}

 <DataGridTemplateColumn Header="DataType" Width="120">
   <DataGridTemplateColumn.CellTemplate>
     <DataTemplate x:DataType="vm:TagViewModel">
       <ComboBox 
                 ItemsSource="{x:Static vm:MainWindowViewModel.DataTypes}"
                 SelectedItem="{Binding DataType, Mode=TwoWay}"/>
     </DataTemplate>
   </DataGridTemplateColumn.CellTemplate>
 </DataGridTemplateColumn>

 <DataGridTemplateColumn Header="数据类型2" Width="120">
   <DataGridTemplateColumn.CellTemplate>
     <DataTemplate x:DataType="vm:TagViewModel">
       <ComboBox  x:CompileBindings="False"           
                 ItemsSource="{Binding $parent[DataGrid].DataContext.DataTypeList}}"
                 SelectedItem="{Binding DataType2, Mode=TwoWay}"/>
     </DataTemplate>
   </DataGridTemplateColumn.CellTemplate>
 </DataGridTemplateColumn>

Expected behavior

No response

Avalonia version

11.2.6

OS

Windows

Additional context

No response

[langsisi]

demo
DatagridDemo.zip

[WCKYWCKF]

This is not a bug. The reason is that the binding for SelectedItem may complete before the binding for ItemsSource, making your initial value setting ineffective. In this case, the SelectedItem you set does not exist in the ItemsSource. You can resolve this issue through some design changes, such as subscribing to the ValueChanged event of ComboBox.ItemsSource and binding ComboBox.SelectedItem after it is not null.