R – Can you build an entire application in Silverlight

You can throw and capture data validation exceptions.

To manage both of these types of errors need to take 3 steps:

1. Identify the error handler either in the control or higher in the visiblity hierarchy (e.g., a container; in this case the grid that contains the text box)
2. Set NotifyOnValidationError and ValidateOnException to true. The latter tells the Binding Engine to create a validation error event when an exception occurs. The former tells the Binding Engine to raise the BindingValidationError event when a validation error occurs.
3. Create the event handler named in step 1.

Taken from here.

Sample code:

// page.xaml.cs

private bool clean = true;


private void LayoutRoot_BindingValidationError( 
   object sender, ValidationErrorEventArgs e )
{
   if ( e.Action == ValidationErrorEventAction.Added )
   {
      QuantityOnHand.Background = new SolidColorBrush( Colors.Red );
      clean = false;
   }
   else if ( e.Action == ValidationErrorEventAction.Removed )
   {
      QuantityOnHand.Background = new SolidColorBrush( Colors.White );
      clean = true;
   }
}



// page.xaml

<Grid x:Name="LayoutRoot" Background="White" BindingValidationError="LayoutRoot_BindingValidationError" >

<TextBox x:Name="QuantityOnHand"   
    Text="{Binding Mode=TwoWay, Path=QuantityOnHand, 
        NotifyOnValidationError=true,  ValidatesOnExceptions=true }"
    VerticalAlignment="Bottom"
    HorizontalAlignment="Left"
    Height="30" Width="90"red
    Grid.Row="4" Grid.Column="1" />


// book.cs

public int QuantityOnHand
{
   get { return quantityOnHand; }
   set
   {
      if ( value < 0 )
      {
         throw new Exception( "Quantity on hand cannot be negative!" );
      }
      quantityOnHand = value;
      NotifyPropertyChanged( "QuantityOnHand" );
   }       // end set
}

I would argue that you CAN port Silverlight to WPF with minimal effort. I spent 2 hours porting and application I spent 3 weeks writing. I would argue that those 2 hours spent would categorize as minimal effort.

Sure, you need to create a new project, add the files to the new project and tweak them.

Since Silverlight is a subset of WPF its allot easier to go from Silverlight to WPF than the other way around.

For business logic and non-UI code your code should port almost straight across. I had some minor issues around authentication, as Silverlight 2 will pick up any authentication information in the browser, while in WPF you have to role your own login screen and manage cookies etc.

For the XAML it will port straight across if you don't style your controls. If you style your controls the use of the Visual State Manager, currently missing in WPF, will make things a little trickier. You can either re-style your controls in WPF using Triggers, or you can use the VSM implementation for WPF done by John Gossman. Microsoft have announced that they will add the VSM to WPF to make the two frameworks more compatible.

The perhaps most important reuse tough, is skills and experience. Since the two platforms are so similar you will be able to reuse all your skills in WPF.

I recently did a blog post about the Dive Log sample application and how I ported it from Silverlight 2 to WPF. Might give you some idea of the process.