Preliminary MealsController#create

app/models/ingredient.rb

@@ -1,8 +1,14 @@
 class Ingredient < ActiveRecord::Base
-  belongs_to :composition, inverse_of: :ingredients, required: true
+  belongs_to :composition, inverse_of: :ingredients, polymorphic: true, required: true
   belongs_to :food, required: true
   belongs_to :part_of, required: false
 
   validates :ready_ratio, numericality: {greater_than_or_equal_to: 0.0}
   validates :amount, numericality: {greater_than_or_equal_to: 0.0}
+
+  after_initialize do
+    if new_record?
+      self.ready_ratio ||= BigDecimal.new('1.0')
+    end
+  end
 end

app/models/meal.rb

@@ -1,7 +1,8 @@
 class Meal < ActiveRecord::Base
   belongs_to :project, required: true
 
-  has_many :ingredients, as: :composition, dependent: :destroy, validate: true
+  has_many :ingredients, as: :composition, inverse_of: :composition, dependent: :destroy,
+    validate: true
   has_many :foods, through: :ingredients
   validates :ingredients, presence: true
   accepts_nested_attributes_for :ingredients, allow_destroy: true, reject_if: proc { |attrs|