Nick's .NET Travels

Continually looking for the yellow brick road so I can catch me a wizard....

XAML and Databinding Debugging for Windows and Windows Phone

A question that came up today during the //learn/ event was how to debug data binding in Windows and Windows Phone projects.Normally I start by checking out the Output window – in most cases any issue with data binding is usually a naming issue, which will result in a bindingexpression path error in the Output window as follows:

Error: BindingExpression path error: 'test' property not found on 'App4.MainViewModel, App4, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'. BindingExpression: Path='test' DataItem='App4.MainViewModel, App4, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'; target element is 'Windows.UI.Xaml.Controls.TextBlock' (Name='null'); target property is 'Text' (type 'String')

I was reminded that Xmlspy is a great tool for diagnosing XAML issues, as well as data binding expressions. I downloaded the latest version and was surprised to see that there is full support for all types of Windows Phone 8.1 applications. The only issue I saw was getting it to attach to Windows Phone applications but this was due to my firewall getting in the way. Here’s how you can check and fix this issue:

  • Open the XAML Spy Explorer window (View menu–> Other Windows –> XAML Spy Explorer)
  • Click on the “cog” icon in the window toolbar
  • Find the “Enable remote debugging” option and set it to Yes. You’ll be prompted to permit elevated privileges (I assume to configure firewall).

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Now you should be good to debug your application on the emulator/device. The XAML Spy Explorer window will automatically populate with information about your application

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Note that you can debug much more than just XAML, including sensors, storage and package deployment information.

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