yeast model and fg calculations

lib/beerxml/model.rb

@@ -99,5 +99,5 @@ def self.xml_attr_name(name)
   end
 end
 
-%w(hop recipe fermentable).
+%w(hop recipe fermentable yeast).
   each { |f| require "beerxml/#{f}" }

lib/beerxml/recipe.rb

@@ -14,7 +14,7 @@ class Beerxml::Recipe < Beerxml::Model
   has n, :hops
   has n, :fermentables
   # has n, :miscs
-  # has n, :yeasts
+  has n, :yeasts
   # has n, :waters
 
   property :asst_brewer, String
@@ -56,4 +56,9 @@ def calculate_og
     og = 1 + ((total_ppg / batch_size.in_gallons.to_f) * 0.001)
     Beerxml.round(og, 3)
   end
+
+  def calculate_fg
+    og = calculate_og
+    Beerxml.round(og - ((og - 1) * yeasts.first.attenuation * 0.01), 3)
+  end
 end

lib/beerxml/yeast.rb

@@ -0,0 +1,26 @@
+class Beerxml::Yeast < Beerxml::Model
+  include DataMapper::Resource
+
+  property :name, String, :required => true
+  property :type, Enum['Ale', 'Lager', 'Wheat', 'Wine', 'Champagne'], :required => true
+  property :form, Enum['Liquid', 'Dry', 'Slant', 'Culture'], :required => true
+  # TODO: sheesh... this can be a Weight instead, if amount_is_weight
+  property :amount, Volume, :required => true
+
+  property :amount_is_weight, Boolean
+  property :laboratory, String
+  property :product_id, String
+  property :min_temperature, Temperature
+  property :max_temperature, Temperature
+  property :flocculation, Enum[nil, 'Low', 'Medium', 'High', 'Very High']
+  property :attenuation, Float
+  property :notes, String, :length => 65535
+  property :best_for, String
+  property :times_cultured, Integer
+  property :max_reuse, Integer
+  property :add_to_secondary, Boolean
+
+  # these are not used in the xml
+  property :id, Serial
+  belongs_to :recipe, :required => false
+end

spec/parsing_spec.rb

@@ -101,6 +101,26 @@ def check_parse(klass, file, node, attrs)
         :hsi => 35.0,
       })
     end
+    it "should parse yeasts" do
+      check_parse(Beerxml::Yeast, "yeast", 3, {
+        :name => 'European Ale',
+        :type => 'Ale',
+        :form => 'Liquid',
+        :amount => 0.035,
+        :amount_is_weight => false,
+        :laboratory => 'White Labs',
+        :product_id => 'WLP011',
+        :min_temperature => 18.3,
+        :max_temperature => 21.1,
+        :flocculation => 'Medium',
+        :attenuation => 67.5,
+        :notes => "Malty, Northern European ale yeast.  Low ester production, low sulfer, gives a clean profile.  Low attenuation contributes to malty taste.",
+        :best_for => "Alt, Kolsch, malty English Ales, Fruit beers",
+        :max_reuse => 5,
+        :times_cultured => 0,
+        :add_to_secondary => false,
+      })
+    end
     it "should parse recipes" do
       recipe = check_parse(Beerxml::Recipe, "recipes", 3, {
         :name => 'Dry Stout',

spec/recipes_spec.rb

@@ -12,4 +12,10 @@
     recipe.should be_valid
     recipe.calculate_og.should == 1.056
   end
+
+  it "should calculate the FG for an all grain batch" do
+    recipe = Beerxml::Recipe.new.from_xml(read_xml("recipes").root.children[1])
+    recipe.should be_valid
+    recipe.calculate_fg.should == 1.016
+  end
 end