Moved Formula to separate model

app/models/formula.rb

@@ -0,0 +1,58 @@
+class Formula < ActiveRecord::Base
+  include BodyTracking::FormulaBuilder
+
+  attr_reader :parts, :quantities
+
+  belongs_to :quantity, inverse_of: :formula, required: true
+
+  validates :code, presence: true
+  validate do
+    parse.each { |message, params| errors.add(:code, message, params) }
+  end
+
+  after_initialize do
+    if new_record?
+      self.zero_nil = true if self.zero_nil.nil?
+    end
+  end
+
+  private
+
+  def parse
+    parser = FormulaBuilder.new(self.code)
+    identifiers, parts = parser.parse
+    errors = parser.errors
+
+    quantities = Quantity.where(project: self.quantity.project, name: identifiers)
+    quantities_names = quantities.pluck(:name)
+    (identifiers - quantities_names).each do |q|
+      errors << [:unknown_quantity, {quantity: q}]
+    end
+
+    @parts, @quantities = parts, quantities.to_a if errors.empty?
+    errors
+  end
+
+  def calculate(inputs)
+    quantities = inputs.map { |q, v| [q.name, v.transpose[0]] }.to_h
+    length = quantities.values.first.length
+
+    raise(InvalidFormula, 'Invalid formula') unless self.valid?
+    raise InvalidInputs unless quantities.values.all? { |v| v.length == length }
+
+    args = []
+    @parts.each do |p|
+      code = p[:type] == :indexed ?
+        "length.times.map { |index| #{p[:content]} }" : p[:content]
+      args << get_binding(quantities, args, length).eval(code)
+    end
+    args.last.map { |v| [v, nil] }
+  rescue Exception => e
+    puts e.message
+    [[nil, nil]] * length
+  end
+
+  def get_binding(quantities, args, length)
+    binding
+  end
+end

app/models/quantity.rb

@@ -1,6 +1,4 @@
 class Quantity < ActiveRecord::Base
-  include BodyTracking::Formula
-
   enum domain: {
     diet: 0,
     measurement: 1,
@@ -18,12 +16,16 @@ class Quantity < ActiveRecord::Base
   has_and_belongs_to_many :column_views
   has_many :readouts
 
+  has_one :formula, inverse_of: :quantity, dependent: :destroy, validate: true
+  accepts_nested_attributes_for :formula, allow_destroy: true, reject_if: proc { |attrs|
+    attrs['code'].blank?
+  }
+
   validates :name, presence: true, uniqueness: {scope: :project_id}
   validates :domain, inclusion: {in: domains.keys}
   validate if: -> { parent.present? } do
     errors.add(:parent, :parent_domain_mismatch) unless domain == parent.domain
   end
-  validates :formula, formula: {allow_nil: true}
 
   after_initialize do
     if new_record?
@@ -31,8 +33,6 @@ class Quantity < ActiveRecord::Base
     end
   end
 
-  delegate :valid?, :quantities, :calculate, to: :f_obj, prefix: :formula, allow_nil: true
-
   def movable?(direction)
     case direction
     when :up
@@ -58,10 +58,4 @@ class Quantity < ActiveRecord::Base
 
     quantities
   end
-
-  private
-
-  def f_obj
-    Formula.new(self.project, self.formula) if self.formula?
-  end
 end

app/views/quantities/_index.html.erb

@@ -43,7 +43,7 @@
           </td>
           <td class="domain"><%= q.domain %></td>
           <td class="description"><%= q.description %></td>
-          <td class="formula"><%= checked_image q.formula? %></td>
+          <td class="formula"><%= checked_image q.formula %></td>
           <td class="action unwrappable">
             <%= link_to l(:button_edit), edit_quantity_path(q), {
               remote: true,

db/migrate/001_create_schema.rb

@@ -11,7 +11,6 @@ class CreateSchema < ActiveRecord::Migration
       t.references :project
       t.integer :domain
       t.string :name
-      t.string :formula
       t.string :description
       # fields for awesome_nested_set
       t.references :parent
@@ -20,6 +19,13 @@ class CreateSchema < ActiveRecord::Migration
       t.timestamps null: false
     end
 
+    create_table :formulas do |t|
+      t.references :quantity
+      t.string :code
+      t.boolean :zero_nil
+      t.timestamps null: false
+    end
+
     create_table :column_views do |t|
       t.references :project
       t.string :name

db/migrate/002_load_defaults.rb

@@ -138,7 +138,7 @@ class LoadDefaults < ActiveRecord::Migration
         # Calculated quantities go at the and to make sure dependencies exist
         e2 = Quantity.create project: nil, domain: :diet, parent: e1, name: "Calculated",
           description: "Total energy calculated from macronutrients",
-          formula: "4*(Proteins || 0) + 9*(Fats || 0) + 4*(Carbohydrates || 0)"
+          formula_attributes: {code: "4*Proteins + 9*Fats + 4*Carbohydrates", zero_nil: true}
 
         Source.create project: nil, name: "nutrition label",
           description: "nutrition facts taken from package nutrition label"

lib/body_tracking/formula_builder.rb

@@ -1,84 +1,11 @@
 module BodyTracking
-  module Formula
+  module FormulaBuilder
     require 'ripper'
     require 'set'
 
     class InvalidFormula < RuntimeError; end
     class InvalidInputs < RuntimeError; end
 
-    class Formula
-      def initialize(project, formula)
-        @project = project
-        @formula = formula
-        @parts = nil
-        @quantities = nil
-      end
-
-      def validate
-        parser = FormulaBuilder.new(@formula)
-        identifiers, parts = parser.parse
-        errors = parser.errors
-
-        quantities = Quantity.where(project: @project, name: identifiers)
-        quantities_names = quantities.pluck(:name)
-        (identifiers - quantities_names).each do |q|
-          errors << [:unknown_quantity, {quantity: q}]
-        end
-
-        @parts, @quantities = parts, quantities if errors.empty?
-        errors
-      end
-
-      def valid?
-        @quantities || self.validate.empty?
-      end
-
-      def quantities
-        raise(InvalidFormula, 'Invalid formula') unless self.valid?
-
-        @quantities.to_a
-      end
-
-      def calculate(inputs)
-        quantities = inputs.map { |q, v| [q.name, v.transpose[0]] }.to_h
-        length = quantities.values.first.length
-
-        raise(InvalidFormula, 'Invalid formula') unless self.valid?
-        raise InvalidInputs unless quantities.values.all? { |v| v.length == length }
-
-        args = []
-        @parts.each do |p|
-          code = p[:type] == :indexed ?
-            "length.times.map { |index| #{p[:content]} }" : p[:content]
-          args << get_binding(quantities, args, length).eval(code)
-        end
-        args.last.map { |v| [v, nil] }
-      rescue Exception => e
-        puts e.message
-        [[nil, nil]] * length
-      end
-
-      private
-
-      def get_binding(quantities, args, length)
-        binding
-      end
-    end
-
-
-    class FormulaValidator < ActiveModel::EachValidator
-      def initialize(options)
-        super(options)
-      end
-
-      def validate_each(record, attribute, value)
-        Formula.new(record.project, value).validate.each do |message, params|
-          record.errors.add(attribute, message, params)
-        end
-      end
-    end
-
-
     # List of events with parameter count:
     # https://github.com/racker/ruby-1.9.3-lucid/blob/master/ext/ripper/eventids1.c
     class FormulaBuilder < Ripper::SexpBuilder