HyperlinkButton Gotcha

The new Silverlight 2 HyperlinkButton control is one of the few controls that there is no exact match for between Silverlight 2 and WPF, and its use is quite simple. You specify a value for the NavigateUri property, which defines where the link will navigate to (it's all in the name!) and also specify a value for the TargetName property, which defines the target window or frame to navigate such as _blank, or _self.

The following code examples show how to define a HyperlinkButton that shows "Titan Blog" and will navigate to this blog in a new window:

<HyperlinkButton Content="Titan Blog"

                 NavigateUri="http://cloudstore.spaces.live.com"

                 TargetName="_blank" />

The type of the NavigateUri property is actually a Uri. Like a lot of properties in WPF and Silverlight 2, you can specify a string instead of an instance of the actual type and a converter is used to convert the source string into the required type (such as Background="Red" being converted into a SolidColorBrush). This is what happens to the sting specified in the NavigateUri property in the previous code example. The following code example shows how to define the previous HyperlinkButton in code:

HyperlinkButton targetLink = new HyperlinkButton();
targetLink.Content = "Titan Blog";
targetLink.NavigateUri = new Uri("http://cloudstore.spaces.live.com");
targetLink.TargetName = "_blank";

Get to the point, Derek! Well the point is this: when it comes to data-binding to a HyperlinkButton control, you might be tempted to bind a string to the NavigateUri property. Don't! Whilst this doesn't bring about a catastrophic end to your application, it also won't result in your HyperlinkButton actually working. There are two potential solutions to this problem.

1. Bind a Uri value to the NavigateUri property. This is fine if you have control over the underlying data model that you are binding to and provides the simplest solution.
2. Create a custom converter that can convert a string to a Uri. Whilst this is a particularly simple converter to write, it will muddy up your nice neat XAML by requiring you to specify the converter in the binding.

I used solution 1 this time around because I had access to my data model and could change it easily, but in the future, I could just as easily be tempted to use option 2.