I've gotten around to installing Windows and setting up Visual Studio to run with my new Umbraco 5 installation. I am attemptning to select all nodes in my tree, based on whether or not a field is set to true. The field is called topNavigation. I want to use be able to use intellisense and at the moment I am fiddling with the following code:

@inherits PartialViewMacroPage
@using Umbraco.Cms.Web
@using Umbraco.Cms.Web.Macros
@using Umbraco.Framework

@{
    // I want to get all nodes that have a field set to true.
    var root = @Model.CurrentPage.AncestorContentOrSelf().Last();
    var topNavigation = @root.DescendantContentOrSelf().Where("topNavigation = True");
}

<ul id="navigation">
    @{
        // Here I want to do a foreach on the result.    
    }
</ul>

The part where I use the where mthod fails because IEnumerable does not contain that method.

Any ideas?