def self.search(params)
    orders = self
    orders = orders.scoped(:conditions => {:service_type => params[:service_type]}) if params[:service_type].present?
    orders = orders.scoped(:conditions => ['orders.created_at >= ?', params[:date_range_start]]) if params[:date_range_start].present?
    orders = orders.scoped(:conditions => ['orders.created_at <= ?', params[:date_range_end]]) if params[:date_range_end].present?
    orders.all
  end