Security Rules - Extension to App

[phillgilchrist]

Hi...

Trying to secure an extension availability via custom property... 

Works fine resource.@cpv = user.@cpv

but doesn't work when trying to app.@cpv...

Assuming this can be done...

Have tried:

referencing app.@cpv

adding app to Resource, so resource.app.@cpv = resource.extension.@cpv

and a few other mutations...

Thanks

Phill