this is a weird one...

i've a property on a doctype that uses the MultiNodeTreePicker.

in a controller, i do this to get the property value and it works as expected:

var values = model.Content.GetPropertyValue<IEnumerable<IPublishedContent>>("myMultiNodeTreePickerPropertyAlias");

trick is, i want to put the guid's of the items that are picked into my examine index so i tried this in my start up class (inheriting from IApplicationEventHandler):

public void OnApplicationStarted(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
{
    var helper = new UmbracoHelper(UmbracoContext.Current);

    var myindexer = ExamineManager.Instance.IndexProviderCollection["MyIndexer"];
    myindexer.GatheringNodeData += (sender, e) => mySite_GatheringNodeData(sender, e, helper);
}

private static void myindexerSite_GatheringNodeData(object sender, IndexingNodeDataEventArgs e, UmbracoHelper helper)
{
    try
    {
        var content = helper.TypedContent(e.NodeId);

        var values = content.GetPropertyValue<IEnumerable<IPublishedContent>>("myMultiNodeTreePickerPropertyAlias");

        var valueKeys = new List<string>();
        foreach (var value in values)
        {
            valueKeys.Add(value.GetKey().ToString());
        }

        e.Fields.Add("values", string.Join(" ", valueKeys));
    }
    catch (InvalidOperationException)
    {
    }
}

it throws an exception saying that 'vales' is null! weird...

a bit of debugging and it turns out the property isn't returning as IEnumerable<IPublishedContent> it's coming back as IEnumerable<Udi>. if i update the code to:

private static void myindexerSite_GatheringNodeData(object sender, IndexingNodeDataEventArgs e, UmbracoHelper helper)
{
    try
    {
        var content = helper.TypedContent(e.NodeId);

        var values = content.GetPropertyValue<IEnumerable<Udi>>("myMultiNodeTreePickerPropertyAlias");

        var valueKeys = new List<string>();
        foreach (var value in values)
        {
            valueKeys.Add(GuidUdi.Parse(value.ToString()).Guid.ToString());
        }

        e.Fields.Add("values", string.Join(" ", valueKeys));
    }
    catch (InvalidOperationException)
    {
    }
}

then everything works as expected!

so, my question is: why is the 'MultiNodeTreePicker' returning an IEnumerable<IPublishedContent> in a controller but then returns a IEnumerable<Udi> in the start up class?!

bit of a head scratcher...