def resolve_relationships(rels)
      Hash[rels.map do |name, v|
        rname = [:_has_one, :_has_many].map do |k|
          ra = @resource_mapping_class.representable_attrs[k]
          next nil unless ra
          r = ra.find {|r| r[:as].to_sym == name.to_sym }
          r ? r[:name] : nil
        end.compact.first
        raise "Unknown rel: #{name}" unless rname
        [rname, v]
      end]
    end
def resolve_relationships(rels)
      Hash[rels.map do |name, v|
        rname = [:_has_one, :_has_many].map do |k|
          ra = @resource_mapping_class.representable_attrs[k]
          next nil unless ra
          r = ra.find {|r| r[:as].to_sym == name.to_sym }
          r ? r[:name] : nil
        end.compact.first
        raise "Unknown rel: #{name}" unless rname
        [rname, v]
      end]
    end
TODO: Move/fix this (mapping should expose some clean way to inspect relationships) !