Spree::Variant.find_by_options

variant_decorator.rb

Spree::Variant.class_eval do

  # find variants matching the given map of option_type.id's to option_value.id's
  # and optionally limited to one product
  # Spree::Variant.find_by_options {'4'=>'14','1'=>'3',2=>6, 3=>10}, product

  def self.find_by_options opts={}, product=nil
      sovv = Arel::Table.new :spree_option_values_variants
      sot = Spree::OptionType.arel_table
      sov = Spree::OptionValue.arel_table

      variant = self.arel_table
      relation = variant.project(Arel.sql(self.table_name+'.*'))

      opts.each_with_index do |(option_type_id, option_value_id), i|
          sovv_a = sovv.alias "sovv_#{i}"
          sot_a = sot.alias "sot_#{i}"
          sov_a = sov.alias "sov_#{i}"
          relation = relation.join(sovv_a).on( sovv_a[:variant_id].eq(variant[:id]) ).
                     join(sov_a).on( sov_a[:id].eq(sovv_a[:option_value_id]) ).
                     join(sot_a).on( sot_a[:id].eq(sov_a[:option_type_id]) ).
                     where( sot_a[:id].eq(option_type_id) ).
                     where( sov_a[:id].eq(option_value_id) )
      end

      if product && product.respond_to?(:id)
        relation = relation.where(variant[:product_id].eq(product.id))
      end

      self.find_by_sql(relation.to_sql)
  end

  # v.project(Arel.sql('*')).join(sovv).on(sovv[:variant_id].eq(v[:id])).join(sov2).on(sov[:id].eq(sovv[:option_value_id])).join(sot).on(sot[:id].eq(sov2[:option_type_id])).where(sot[:id].eq(4)).where(sov2[:id].eq(14)).to_sql

end