How to make Resharper resolve path for CustomBinding MarkupExtension

Question

I want to create some extended Binding-Markup-Extension, which behaves just like a normal WPF-Binding but does some things more (use different defaults, maybe add some behavior, etc.). Code looks like this:

public class CustomBindingExtension : Binding
{
  .. some extra properties and maybe overrides ...
}

It all works fine including XAML-intellisense, except I just can't make Resharper resolve my Binding-Path correctly. I.e.: using this code I can [Strg]+Click on 'CurrentText' and Resharper lets vs2010 navigate to the code defining the CurrentText-Property.

<UserControl x:Name="uc" ...>
  <TextBox Text="{Binding ViewModel.CurrentText, ElementName=uc}" />
</UserControl>

But using my binding, which works correctly at runtime, I just get a Tooltip when hovering 'CurrentText' telling me it is some 'MS.Internal.Design.Metadata.ReflectionTypeNode', and no navigation via [Strg]+Click.

<UserControl x:Name="uc" ...>
  <TextBox Text="{util:CustomBinding ViewModel.CurrentText, ElementName=uc}" />
</UserControl>

I tried the following things:

Derive from Binding

Derive from BindingDecoratorBase

Leave out the 'Extension' suffix for my CustomBinding-class

put the Markup-Extension in a separate assembly

Use ConstructorArgumentAttribute

Property of type string and type PropertyPath for the Path-Property

I also looked at the original classes Binding and BindingBase, but could not find any more difference to my code. Any ideas what should help here? Or is this just a special treatment of the Binding-MarkupExtension which I can in no way get for my own MarkupExtensions?

Update 16.03.2011: Might also be bug or deficiency of Resharper, Jetbrains is investigating the issue: http://youtrack.jetbrains.net/issue/RSRP-230607

Update 10.12.2013: Meanwhile, the feature seems to be working (with R# 7.1.3, maybe also earlier versions), I actually use the approach with the BindingDecoratorBase and I like it a lot. Maybe it only works, if your MarkupExtension ends on 'Binding', but mine does, so I am happy.

Xenon

I didn't even know you could do that. When I try it (with a regular Binding) I always get the behavior you get when you use the CustomBinding. Anything special I should do in order to get it working? – Shieh

Yeah, Ctrl+Click on CurrentText just selects the word for me. Are you sure that's not an extension that is jumping to the definition? Maybe the Productivity Power Tools? – Colossus

Ok, I was not sure about that, seems to be a Resharper-feature. Of course it only works if you are binding to something type-safe like the ViewModel and not the DataContext. – Xenon

It is a feature from Resharper, I will clarify this in the question. – Xenon

Answer 1

Actually it's not possible in current versions of R# and, unfortunately, still be missing feature of upcoming R# 6.1 release.

This feature requires a lot of infrastructure changes, but it's on our list and definitely will be implemented in R# 7. Seems like [CustomBindingMarkup] and [BindingPath] (for path constructor parameter and the Path property) attributes will be introduced.

We really apologize for any inconvenience.

Launcher

+1 This would be a really helpful feature.... hopefully it will make it in to Resharper 7.0 – Rusel

I have Resharper 7.1 installed and I'm still seeing this issue. Is this fix implemented yet and is there any documentation for how to enable it? – Misprision

Are there any news on further implementation plans? – Botanical

Answer 2

You should access your custom Markup-Extension, using the correct namespace:

<UserControl x:Name="uc" ...
xmlns:ext="clr-ns:YourProjectNamespace">
  <TextBox Text="{ext:CustomBinding ViewModel.CurrentText, ElementName=uc}" />
</UserControl>

Here is a nice article about creating custom Markup-Extensions.

Carducci

Yeah, that's right. I corrected my code sample. Unfortunately, it does not solve the actual problem, in my tests I had the namespace in the xaml, otherwise the whole thing had failed to compile. – Xenon

Answer 3

One way to fool R# is to name it Binding:

public class Binding : MarkupExtension
{
    public Binding()
    {
    }

    public Binding(string path)
    {
        Path = path;
    }

    public string Path { get; set; }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        return 5;
    }
}

Then it works the same as standard binding with R#

<TextBlock Text="{custom:Binding SomeProp}" />

Topper