module ActiveAdmin::ResourceController::Scoping

def begin_of_association_chain

If scope_to is a proc, we eval it, otherwise we call the method on the controller.

the scope to be defined in the active admin configuration.
Override the default InheritedResource #begin_of_association_chain to allow 
def begin_of_association_chain
  return nil unless active_admin_config.scope_to
  case active_admin_config.scope_to
  when Proc
    instance_eval &active_admin_config.scope_to
  when Symbol
    send active_admin_config.scope_to
  else
    raise ArgumentError, "#scope_to accepts a symbol or a block"
  end
end