WPF .Net Core 6 RelayCommand Problem

[Kevin Marois]

I'm trying to create a simple log in window. The Sign In button does not get enabled. The CanExecuteChange fires on startup, but never after that. You can see that I'm using the Community Toolkit. I've also tried the RelayCommand in my own framework. Neither work. I have also tried

CommandManager.InvalidateRequerySuggested();

in the UserName and Password properties. Here's the Sign In button

Here's the View Model

using CommunityToolkit.Mvvm.Input;
using Marois.Framework.Core.Shared;
using System.Windows.Input;

namespace Jayhawk.UI.WPF.ViewModels
{
public class LoginViewModel : _DialogViewModelBase
{
#region Private Fields
private readonly IEventAggregator _eventAggregator;
#endregion

    #region Properties
    private string? \_UserName;
    public string? UserName
    {
        get { return \_UserName; }
        set
        {
            SetProperty(nameof(UserName), ref \_UserName, value);
        }
    }

    private string? \_Password;
    public string? Password
    {
        get { return \_Password; }
        set
        {
            SetProperty(nameof(Password), ref \_Password, value);
        }
    }

    private bool \_IsRememberMeChecked;
    public bool IsRememberMeChecked
    {
        get { return \_IsRememberMeChecked; }
        set
        {
            SetProperty(nameof(IsRememberMeChecked), ref \_IsRememberMeChecked, value);
        }
    }

    private bool \_IsLoggingIn;
    public bool IsLoggingIn
    {
        get { return \_IsLoggingIn; }
        set
        {
            SetProperty(nameof(IsLoggingIn), ref \_IsLoggingIn, value);
        }
    }
    #endregion

    #region Commands
    private ICommand? \_SignInCommand;
    public ICommand? SignInCommand
    {
        get
        {
            if (\_SignInCommand == null)
                \_SignInCommand = new RelayCommand(SignInExecuted, SignInCanExecute);
            return \_SignInCommand;
        }
    }
    #endregion

    #region CTOR
    public LoginViewModel()
    {
    }
    #endregion
    
    #region Private Methods
    priv

[Richard Deeming]

Looking at the source code for CommunityToolkit.Mvvm.Input.RelayCommand[^], it doesn't use the CommandManager at all. You need to explicitly call the NotifyCanExecuteChanged method[^] instead. NB: That SetProperty method looks odd - any relatively recent framework would use [CallerMemberName] so that you don't need to pass the name of the property:

protected bool SetProperty(ref T storage, T value, [CallerMemberName] string propertyName = null)
{
if (Equals(storage, value)) return false;

storage = value;
OnPropertyChanged(propertyName);
return true;

}

public string? UserName
{
get { return _UserName; }
set { SetProperty(ref _UserName, value); }
}

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