How to bind ExpandoObject in Avalonia 12 after removal of IPropertyAccessorPlugin / BindingPlugins

[langsisi]

In Avalonia 11 and earlier versions, I used a custom IPropertyAccessorPlugin registered via BindingPlugins.PropertyAccessors.Insert(0, ...) to support direct binding to ExpandoObject using standard {Binding PropertyName} syntax in XAML.

// Avalonia 11 working code
BindingPlugins.PropertyAccessors.Insert(0, new AvaloniaDynamicPropertyAccessorPlugin());

Starting from Avalonia 12, the entire BindingPlugins, IPropertyAccessorPlugin and related binding plugin infrastructure has been removed.
Now my existing logic for binding ExpandoObject no longer works.

Avalonia 12，I use ExpandoObjectWrapper

using CommunityToolkit.Mvvm.Input;
using System.Collections.Generic;
using System.Dynamic;
namespace AvaloniaApplication12.ViewModels;
public partial class MainViewModel : ViewModelBase
{
    private int i = 0;
    public ExpandoObjectWrapper ParamsWrapper { get; set; }
    public MainViewModel()
    {
        ParamsWrapper = new ExpandoObjectWrapper();
        ((IDictionary<string, object>)ParamsWrapper.GetExpando()).Add("Name", "InitialValue");
      
        ParamsWrapper.LoadExpando();
    }

    [RelayCommand]
    private void Refresh()
    {
        var dict = (IDictionary<string, object>)ParamsWrapper.GetExpando();
        dict["Name"] = $"Text{i}";
        i++;
        ParamsWrapper.LoadExpando();
    }

   
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Dynamic;

namespace AvaloniaApplication12.ViewModels;

public class ExpandoObjectWrapper : INotifyPropertyChanged
{
    private readonly Dictionary<string, object?> _store = new();
    private ExpandoObject _innerExpando = new();

    public ExpandoObject GetExpando() => _innerExpando;

    public void LoadExpando()
    {
        var dict = (IDictionary<string, object?>)_innerExpando;
        _store.Clear();
        foreach (var kv in dict)
        {
            _store[kv.Key] = kv.Value;
        }
        OnPropertyChanged(string.Empty);
    }

    public object? this[string key]
    {
        get
        {
            _store.TryGetValue(key, out var v);
            return v;
        }
        set
        {
            _store[key] = value;
            ((IDictionary<string, object?>)_innerExpando)[key] = value;
            OnPropertyChanged(string.Empty);
        }
    }

    public event PropertyChangedEventHandler? PropertyChanged;
    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

When using indexer binding syntax {Binding Wrapper[Key]} in Avalonia 12 stable:
OnPropertyChanged("Item[Key]") has no effect
OnPropertyChanged("[Key]") has no effect
Only OnPropertyChanged(string.Empty) can trigger UI refresh for index bindings.
There is no supported way to send targeted property change notification for indexer bindings, which forces full object refresh every time any dynamic key changes.

[maxkatz6]

OnPropertyChanged("Item[Key]") has no effect

OnPropertyChanged($"Item[{key}]") should work, like OnPropertyChanged($"Item[Name]"), not a hardcoded "Key", unless I misunderstood.

[langsisi]

Thank you for the advice.
I've tried OnPropertyChanged($"Item[{key}]") resulting in Item[Name], but the indexer binding {Binding ParamsWrapper[Name]} still won't refresh UI. Only OnPropertyChanged(string.Empty) works.

    <StackPanel>
        <TextBlock Text="{Binding ParamsWrapper[Name]}" HorizontalAlignment="Center" VerticalAlignment="Center"/>
        <TextBox Text="{Binding ParamsWrapper[Name], Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" />
        <Button Content="Click Me" Command="{Binding RefreshCommand}"/>
    </StackPanel>

[maxkatz6]

Another opportunity is to implement IReflectableType + INotifyPropertyChanged instead of having a dictionary.
In IReflectableType's implementation you can return a type-info containing list of your dynamic properties and pass their getter/setter.
And keep INotifyPropertyChanged for OnPropertyChanged(propertyName) as it would be a normal object.

[maxkatz6]

One thing I am not sure about IReflectableType support - you might need to use ReflectionBinding there instead of compiled bindings that are there by default.