Simple utility for working with polymorphic associations in ActiveRecord where queries.

polymorphic_query_helper.rb

module PolymorphicQueryHelper

  class << self
    def expand_polymorphic_hash(hash)
      {}.tap do |expanded_hash|
        for name, object in hash
          expanded_hash.merge!({
            "#{name}_id".to_sym => object.id,
            "#{name}_type".to_sym => object.class.name
          })
        end
      end
    end
  end

end

For example:

MyModel.where(PolymorphicQueryHelper.expand_polymorphic_hash({
  polymorphic_association: OtherModel.first
}))

is expanded to

MyModel.where({
  polymorphic_association_id: OtherModel.first.id,
  polymorphic_assocation_type: OtherModel.class.name
})