Using polymorphic relationships in Rails forms with GlobalID

#form
f.input, :groupable_gid, as: :select, collection: [groupable.name, groupable.to_gid]

#polymorphic model
def groupable_gid
  groupable&.to_global_id
end
def groupable_gid=(gid)
  self.groupable = GlobalID::Locator.locate gid
end