gistfile2.txt

product.rb

class Product
  # .. junk
  has_many :prices
  # Returns a hash with the min, max and average for the range defined under
  # the Prices aggregatable scope
  def min_max_avg
    map = "function() { emit(this.product_id, {amount: this.amount, qty: this.qty});}"
    reduce = <<-JS
      function(price_id, vals) {
        var min = vals[0].amount;
        var max = min;
        var E_w = vals[0].qty;
        var E_v = max;
        for (var i = 1; i < vals.length; i++) {
          vals[i].amount < min && (min = vals[i].amount);
          vals[i].amount > max && (max = vals[i].amount);
          E_w += vals[i].qty;
          E_v += vals[i].amount;
        }
        return {min: min, max: max, avg: (E_v/E_w)};
      }
    JS
    # Aggregatable just puts in the condition that recorded_on is at most 5 days in the past
    prices.aggregatable.collection.map_reduce(map,reduce, {:query => {:product_id => id}}).find.to_a#MXDEBUG: whats this return look like
  end
end