How to detect broken WPF Data binding?

Question

While trying to answer a question in the vicinity 'Unit Testing WPF Bindings' I had the following niggling question..
What's the best way to find if you have WPF Data Binding wiring setup incorrectly (or you just broke something that was wired up correctly) ?

Although the unit-testing approach seems to be like Joel's 'ripping off your arm to remove a splinter'.. I am looking around for easier less Overhead ways to detect this.

Everyone seems to have committed themselves to data binding in a big way with WPF.. and it does have its merits.

Answer 1

In .NET 3.5 it was introduced a new way to specifically output tracing information about specific data bindings.

This is done through the new System.Diagnostics.PresentationTraceSources.TraceLevel attached property that you can apply to any binding or data provider. Here is an example:

<Window x:Class="WpfApplication1.Window1"     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     xmlns:diag="clr-namespace:System.Diagnostics;assembly=WindowsBase"     Title="Debug Binding Sample"     Height="300"     Width="300">     <StackPanel>         <TextBox Name="txtInput" />         <Label>             <Label.Content>                 <Binding ElementName="txtInput"                          Path="Text"                          diag:PresentationTraceSources.TraceLevel="High" />             </Label.Content>         </Label>     </StackPanel> </Window> 

This will put trace information for just that particular binding in Visual Studio's Output Window, without any tracing configuration required.

Answer 2

Best I could find...

How can I debug WPF Bindings? by Beatriz Stollnitz

Since everyone can't always keep one eye on the Output Window looking for Binding errors, I loved Option#2. Which is add this to your App.Config

<?xml version="1.0" encoding="utf-8" ?> <configuration>   <system.diagnostics>     <sources>       <source name="System.Windows.Data" switchName="SourceSwitch" >         <listeners>           <add name="textListener" />         </listeners>       </source>      </sources>       <switches>         <add name="SourceSwitch" value="All" />       </switches>        <sharedListeners>         <add name="textListener"         type="System.Diagnostics.TextWriterTraceListener"         initializeData="GraveOfBindErrors.txt" />       </sharedListeners>        <trace autoflush="true" indentsize="4"></trace>    </system.diagnostics> </configuration> 

Pair that up with a good regex scan script to extract out relevant info, that you can run occasionally on the GraveOfBindErrors.txt in your output folder

System.Windows.Data Error: 35 : BindingExpression path error: 'MyProperty' property not found on 'object' ''MyWindow' (Name='')'. BindingExpression:Path=MyProperty; DataItem='MyWindow' (Name=''); target element is 'TextBox' (Name='txtValue2'); target property is 'Text' (type 'String')