Make StockEvent a base class for Delivery and StockTaking

This helps to share code between the two entities and allows easier
extensions in the future.

app/controllers/deliveries_controller.rb

@@ -9,6 +9,7 @@ class DeliveriesController < ApplicationController
 
   def show
     @delivery = Delivery.find(params[:id])
+    @stock_changes = @delivery.stock_changes.includes(:stock_article).order('articles.name ASC')
   end
 
   def new

app/helpers/stockit_helper.rb

@@ -6,15 +6,15 @@ module StockitHelper
   end
 
   def link_to_stock_change_reason(stock_change)
-    if stock_change.delivery_id
+    if stock_change.delivery
       link_to Delivery.model_name.human, supplier_delivery_path(stock_change.delivery.supplier, stock_change.delivery)
-    elsif stock_change.order_id
+    elsif stock_change.order
       link_to Order.model_name.human, order_path(stock_change.order)
-    elsif stock_change.stock_taking_id
+    elsif stock_change.stock_taking
       link_to StockTaking.model_name.human, stock_taking_path(stock_change.stock_taking)
     end
   end
-  
+
   def stock_article_price_hint(stock_article)
     t('simple_form.hints.stock_article.edit_stock_article.price',
       :stock_article_copy_link => link_to(t('stockit.form.copy_stock_article'),

app/models/delivery.rb

@@ -1,12 +1,11 @@
-class Delivery < ApplicationRecord
+class Delivery < StockEvent
 
   belongs_to :supplier
   belongs_to :invoice
-  has_many :stock_changes, -> { includes(:stock_article).order('articles.name ASC') }, :dependent => :destroy
 
   scope :recent, -> { order('created_at DESC').limit(10) }
 
-  validates_presence_of :supplier_id, :date
+  validates_presence_of :supplier_id
   validate :stock_articles_must_be_unique
 
   accepts_nested_attributes_for :stock_changes, :allow_destroy => :true

app/models/stock_change.rb

@@ -1,7 +1,7 @@
 class StockChange < ApplicationRecord
-  belongs_to :delivery
+  belongs_to :delivery, foreign_key: 'stock_event_id'
   belongs_to :order
-  belongs_to :stock_taking
+  belongs_to :stock_taking, foreign_key: 'stock_event_id'
   belongs_to :stock_article
 
   validates_presence_of :stock_article_id, :quantity

app/models/stock_event.rb

@@ -0,0 +1,8 @@
+class StockEvent < ApplicationRecord
+
+  has_many :stock_changes, dependent: :destroy
+  has_many :stock_articles, through: :stock_changes
+
+  validates_presence_of :date
+
+end

app/models/stock_taking.rb

@@ -1,10 +1,4 @@
-class StockTaking < ApplicationRecord
-
-  has_many :stock_changes, :dependent => :destroy
-  has_many :stock_articles, :through => :stock_changes
-
-  validates_presence_of :date
-
+class StockTaking < StockEvent
   def stock_change_attributes=(stock_change_attributes)
     for attributes in stock_change_attributes
       stock_changes.build(attributes) unless attributes[:quantity].to_i == 0

app/views/deliveries/show.html.haml

@@ -24,7 +24,7 @@
       %th.numeric= t '.sum'
   %tbody
     - total_net, total_gross = 0,0
-    - @delivery.stock_changes.each do |stock_change|
+    - @stock_changes.each do |stock_change|
       - quantity = stock_change.quantity
       - sum = quantity * stock_change.stock_article.price
       - total_net += sum