ReactiveUI Validation Does not raise Error Notification And Failed To BindValidation

Question

Hello, I try to use ReactiveUI.Validation package To Validate Wpf Simple App And Validation works i can see it in ViewModel valid state But I can not see any notification to view element I mean no red border or any type of error appear, even when using MaterialDesignPackage, Custome Templates nothing works!

ViewModel.cs

public class AddNewUserViewModel : ReactiveValidationObject
{
    private string _email;
    public string Email
    {
        get => _email;
        set => this.RaiseAndSetIfChanged(ref _email, value);
    }

    public ReactiveCommand Start { get; }
    public AddNewUserViewModel()
    {
        var vEmailHelper = this
            .ValidationRule(viewModel => viewModel.Email, e => e?.Length > 2, "Error Email Message");
        var canStart = this.IsValid();
        Start = ReactiveCommand.Create(() => { }, canStart);
    }
}

View.cs

public partial class AddNewUserDialogView : ReactiveWindow
{
    public AddNewUserDialogView()
    {
        ViewModel = new AddNewUserViewModel();
        InitializeComponent();
        this.WhenActivated(disposable =>
        {
            this.Bind(ViewModel, viewModel => viewModel.Email, v => v.EmailTextBox.Text)
                .DisposeWith(disposable);
            this.BindCommand(ViewModel, viewModel => viewModel.Start, v => v.ButStart).DisposeWith(disposable);
        });
    }
}

View.cs.xaml

If my EmailText does not match the rule, The button disabled, and this ok But I can not see any behavior of validation in TextBox control itself? I try it with ErrorTemplate but not work also

So how can I show an error or even get any error notifications in view

Also notice: May open it as new question

When I try to bind validation message of specific property it failed


public partial class AddNewUserDialogView : ReactiveWindow
{
    public AddNewUserDialogView()
    {
        ViewModel = new AddNewUserViewModel();
        InitializeComponent();
        this.WhenActivated(disposable =>
        {
            this.Bind(ViewModel, viewModel => viewModel.Email, v => v.EmailTextBox.Text)
                .DisposeWith(disposable);
            this.BindCommand(ViewModel, viewModel => viewModel.Start, v => v.ButStart).DisposeWith(disposable);

            // here
            this.BindValidation(ViewModel, viewModel => viewModel.Email, v => v.ButStart.Content).DisposeWith(disposable);
        });
    }
}

With error :

System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.

This error occurs in CurrentThreadScheduler.cs of ReactiveUI At Line 107

This is a code snippet error location


// Line 85
 SchedulerQueue queue;

            // There is no timed task and no task is currently running
            if (!_running)
            {
                _running = true;

                if (dueTime > TimeSpan.Zero)
                {
                    ConcurrencyAbstractionLayer.Current.Sleep(dueTime);
                }

                // execute directly without queueing
                IDisposable d;
                try
                {
                    d = action(this, state);
                }
                catch
                {
                    SetQueue(null);
                    _running = false;
                    throw; // Line 107
                }

But

When I try to bind The Total/ Ultimate ViewModel error messages it works!


public partial class AddNewUserDialogView : ReactiveWindow
{
    public AddNewUserDialogView()
    {
        ViewModel = new AddNewUserViewModel();
        InitializeComponent();
        this.WhenActivated(disposable =>
        {
            this.Bind(ViewModel, viewModel => viewModel.Email, v => v.EmailTextBox.Text)
                .DisposeWith(disposable);
            this.BindCommand(ViewModel, viewModel => viewModel.Start, v => v.ButStart).DisposeWith(disposable);

            // here
            this.BindValidation(ViewModel, v => v.ButStart.Content).DisposeWith(disposable);
        });
    }
}

resources : i think may be useful

 https://github.com/reactiveui/ReactiveUI.Validation/issues/16
 https://github.com/reactiveui/ReactiveUI.Validation/pull/17
 https://github.com/reactiveui/ReactiveUI.Validation/pull/44

Packages


  
    
    
    
      ..\packages\DynamicData.6.14.8\lib
et461\DynamicData.dll
      True
    
    
      ..\packages\AvalonEdit.5.0.4\lib\Net40\ICSharpCode.AvalonEdit.dll
    
    
      ..\packages\MaterialDesignColors.1.2.2\lib
et45\MaterialDesignColors.dll
    
    
      ..\packages\MaterialDesignThemes.3.0.1\lib
et45\MaterialDesignThemes.Wpf.dll
    
    
    
      ..\packages\Pharmacist.Common.1.5.15\lib
etstandard2.0\Pharmacist.Common.dll
      True
    
    
    
      ..\packages\ReactiveUI.11.2.3\lib
et461\ReactiveUI.dll
      True
    
    
      ..\packages\ReactiveUI.Events.WPF.11.2.3\lib
et461\ReactiveUI.Events.WPF.dll
      True
    
    
      ..\packages\ReactiveUI.Fody.11.2.3\lib
et461\ReactiveUI.Fody.Helpers.dll
      True
    
    
      ..\packages\ReactiveUI.Validation.1.4.10\lib
et461\ReactiveUI.Validation.dll
    
    
      ..\packages\ReactiveUI.WPF.11.2.3\lib
et461\ReactiveUI.WPF.dll
      True
    
    
      ..\packages\ShowMeTheXAML.1.0.12\lib
et45\ShowMeTheXAML.dll
    
    
      ..\packages\ShowMeTheXAML.AvalonEdit.1.0.12\lib
et45\ShowMeTheXAML.AvalonEdit.dll
    
    
      ..\packages\Splat.9.3.11\lib
et461\Splat.dll
      True
    
    
    
    
    
      ..\packages\System.Reactive.4.3.2\lib
et46\System.Reactive.dll
      True
    
    
      ..\packages\System.Runtime.CompilerServices.Unsafe.4.5.2\lib
etstandard2.0\System.Runtime.CompilerServices.Unsafe.dll
      True
    
    
      ..\packages\System.Threading.Tasks.Extensions.4.5.3\lib
etstandard2.0\System.Threading.Tasks.Extensions.dll
      True
    
    
      ..\packages\System.ValueTuple.4.5.0\lib
et47\System.ValueTuple.dll
      True
    
    
    
    
    
      4.0

Updates

I Solve the second problem With very strange modification

This must not be considered a real solution

I just listen to validation status changes

In View

ViewModel.ValidationContext.ValidationStatusChange.Subscribe(x =>
                {
                    // if i omite next line , the solution will not work
                    MessageBox.Show("Start");
                });

And Now Validation Message Appear

 // so: now this line will not produce argument out of range exception
 this.BindValidation(ViewModel, viewModel => viewModel.Email, v => v.ButStart.Content).DisposeWith(disposable);

Also notice: if I listen directly from viewModel the solution will also work

I tested it in another project

But here I separate it because I use different projects from UI/Backendcontains ViewModels

Also notice this will work if I listen to any other validator

So if I expose email ValidationHelper as property out of ViewModel and subscribe to it, this will work,

Also if I just subscribe/listen to email ValidationHelper from ViewModel this will work also

But remember, I still need to call MessageBox.Show("")

Notice: This will work if I Call ShowDialog() on any Window even MainWindow

So the next Solution will also work

ViewModel.ValidationContext.ValidationStatusChange.Subscribe(x =>
                {
                    var v = new MainWindow();
                    v.ShowDialog();
                });

user_11179812 · Answer

Binding the validation to a control template is currently not supported but you can show a validation error message in the view if you bind it to a seperate textblock (Documentation).

If you just want to use the MaterialDesign HelperText to show an error message, you don't need to use ReactiveUI.Validation but could do something like this:

    // Viewmodel
    private ObservableAsPropertyHelper isEmailValid;
    public bool IsEmailValid => isEmailValid.Value;
    ...
    isEmailValid = this.WhenAnyValue(x => x.Email).Select(e => e?.Length > 2).ToProperty(this, nameof(IsEmailValid));

    // View
    this.WhenAnyValue(x => x.ViewModel.IsEmailValid)
        .Do(isValid => HintAssist.SetHint(EmailTextBox, isValid ? string.Empty : "Error Email Message"))
        .Subscribe();

Your second problem should be fixed when you use the latest version of ReactiveUI.Validation (1.4.13).

ReactiveUI Validation Does not raise Error Notification And Failed To BindValidation

Updates

This must not be considered a real solution

1 Answers