class ActiveRecord::PredicateBuilder::RelationHandler

def call(attribute, value)
  if value.eager_loading?
    value = value.send(:apply_join_dependency)
  end
  if value.select_values.empty?
    model = value.model
    if model.composite_primary_key?
      raise ArgumentError, "Cannot map composite primary key #{model.primary_key} to #{attribute.name}"
    else
      value = value.select(value.table[model.primary_key])
    end
  end
  attribute.in(value.arel)
end