WPF MVVM Caliburn Displaying all ErrorMsgs in a specific ViewModel - wpf

Question

I was thinking about displaying error messages to the user in a specific area of the shellview.
So I'm instantiating the ErrorViewModel in my ShellViewModel and it's the ErrorModel is displayed correct. The Textblock withing the ViewModel is displaying it's initialvalue as it should.
But if I pass a string via a public method from another ViewModel (e.g. LoginViewModel) the errorstring is passed to the ErrorViewModel and is also firing the NotifyOfPropertyChange(() => PublishErrorMsg) but the Textblock isnt changing.
Can't see why the content of the textblock won't change.
ErrorViewModel:
public class ErrorViewModel : Screen
{
private string publishErrorMsg;
public string PublishErrorMsg
{
get { return publishErrorMsg; }
set
{
publishErrorMsg = value;
NotifyOfPropertyChange(() => PublishErrorMsg);
}
}
public void ShowError(string msg) {
PublishErrorMsg = msg;
// MessageBox.Show(msg);
NotifyOfPropertyChange(() => PublishErrorMsg);
}
}
XAML ErrorView:
<UserControl x:Class="Views.ErrorView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:Views"
mc:Ignorable="d"
d:DesignHeight="40" d:DesignWidth="800" Background="White">
<Grid>
<DockPanel VerticalAlignment="Bottom" Height="40" Background="#FF474A57">
<TextBlock Text="{Binding PublishErrorMsg}"
Width="200" HorizontalAlignment="Center" VerticalAlignment="Center" Foreground="#FFE69393" FontSize="14">
</TextBlock>
</DockPanel>
</Grid>
Following the part which triggers the event:
public void LogIn() {
this.container.GetInstance<ErrorViewModel>().ShowError("User logged in");
try {
ResetPublishMsg();
ActiveUserModel.CreateIfAuthenticated(UserName, Password);
events.PublishOnUIThread(new LogOnEvent());
}
catch (Exception ex) {
this.container.GetInstance<ErrorViewModel>().PublishErrorMsg = ex.Message;
}
}
Thanks for help!

Answer 1

Maybe have you forgotten to subscribe to event ? see EventAggregator
public class ErrorViewModel : Screen, IHandle<LogOnEvent>
{
private readonly IEventAggregator _eventAggregator;
public ErrorViewModel(IEventAggregator eventAggregator) {
_eventAggregator = eventAggregator;
_eventAggregator.Subscribe(this);
}
public void Handle(LogOnEvent message) {
// Handle the message here.
}
}