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

@@ -6,11 +6,11 @@ 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

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
+class StockTaking < StockEvent
-
-  has_many :stock_changes, :dependent => :destroy
-  has_many :stock_articles, :through => :stock_changes
-
-  validates_presence_of :date
-
   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

db/migrate/20181204070000_create_stock_events.rb

@@ -0,0 +1,41 @@
+class CreateStockEvents < ActiveRecord::Migration
+  class StockEvent < ActiveRecord::Base; end
+  class StockTaking < ActiveRecord::Base; end
+
+  def change
+    rename_table :deliveries, :stock_events
+    rename_column :stock_changes, :delivery_id, :stock_event_id
+    add_column :stock_events, :type, :string, default: 'Delivery', null: false
+
+    reversible do |dir|
+      dir.up do
+        change_column_default :stock_events, :type, nil
+
+        diff = [StockEvent.maximum(:id) + 1 - StockTaking.minimum(:id), 0].max
+
+        execute "UPDATE stock_changes SET stock_event_id = stock_taking_id + #{diff}
+          WHERE stock_taking_id IS NOT NULL"
+        execute "INSERT INTO stock_events (type, id, date, note, created_at)
+          SELECT 'StockTaking', id + #{diff}, date, note, created_at FROM stock_takings"
+
+        remove_column :stock_changes, :stock_taking_id
+        drop_table :stock_takings
+      end
+
+      dir.down do
+        create_table :stock_takings do |t|
+          t.date :date
+          t.text :note
+          t.datetime :created_at
+        end
+        add_column :stock_changes, :stock_taking_id, :integer
+
+        execute "INSERT INTO stock_takings (id, date, note, created_at)
+          SELECT id, date, note, created_at FROM stock_events WHERE type = 'StockTaking'"
+        execute "DELETE FROM stock_events WHERE type = 'StockTaking'"
+        execute "UPDATE stock_changes SET stock_taking_id = stock_event_id, stock_event_id = NULL
+          WHERE stock_event_id IN (SELECT id FROM stock_takings)"
+      end
+    end
+  end
+end

db/schema.rb

@@ -90,16 +90,6 @@ ActiveRecord::Schema.define(version: 20181205010000) do
 
   add_index "bank_transactions", ["financial_link_id"], name: "index_bank_transactions_on_financial_link_id", using: :btree
 
-  create_table "deliveries", force: :cascade do |t|
-    t.integer  "supplier_id", limit: 4
-    t.date     "date"
-    t.datetime "created_at"
-    t.text     "note",        limit: 65535
-    t.integer  "invoice_id",  limit: 4
-  end
-
-  add_index "deliveries", ["supplier_id"], name: "index_deliveries_on_supplier_id", using: :btree
-
   create_table "documents", force: :cascade do |t|
     t.string   "name",               limit: 255
     t.string   "mime",               limit: 255
@@ -472,24 +462,27 @@ ActiveRecord::Schema.define(version: 20181205010000) do
   add_index "settings", ["thing_type", "thing_id", "var"], name: "index_settings_on_thing_type_and_thing_id_and_var", unique: true, using: :btree
 
   create_table "stock_changes", force: :cascade do |t|
-    t.integer  "delivery_id",      limit: 4
+    t.integer  "stock_event_id",   limit: 4
     t.integer  "order_id",         limit: 4
     t.integer  "stock_article_id", limit: 4
     t.integer  "quantity",         limit: 4, default: 0
     t.datetime "created_at"
-    t.integer  "stock_taking_id",  limit: 4
   end
 
-  add_index "stock_changes", ["delivery_id"], name: "index_stock_changes_on_delivery_id", using: :btree
   add_index "stock_changes", ["stock_article_id"], name: "index_stock_changes_on_stock_article_id", using: :btree
-  add_index "stock_changes", ["stock_taking_id"], name: "index_stock_changes_on_stock_taking_id", using: :btree
+  add_index "stock_changes", ["stock_event_id"], name: "index_stock_changes_on_stock_event_id", using: :btree
 
-  create_table "stock_takings", force: :cascade do |t|
+  create_table "stock_events", force: :cascade do |t|
+    t.integer  "supplier_id", limit: 4
     t.date     "date"
-    t.text     "note",       limit: 65535
     t.datetime "created_at"
+    t.text     "note",        limit: 65535
+    t.integer  "invoice_id",  limit: 4
+    t.string   "type",                      null: false
   end
 
+  add_index "stock_events", ["supplier_id"], name: "index_stock_events_on_supplier_id", using: :btree
+
   create_table "supplier_categories", force: :cascade do |t|
     t.string  "name",                           limit: 255, null: false
     t.string  "description",                    limit: 255