#309

backend/app/models/my_discard.rb

@@ -1,7 +1,11 @@
 module MyDiscard
   extend ActiveSupport::Concern
 
-  included { include Discard::Model }
+  included do
+    include Discard::Model
+
+    default_scope -> { kept }
+  end
 
   class_methods do
     def find_undiscard_or_create_by! attrs, &block

backend/app/models/post_version.rb

@@ -1,29 +1,13 @@
 class PostVersion < ApplicationRecord
-  before_update do
-    raise ActiveRecord::ReadOnlyRecord, '版は更新できません．'
-  end
-
-  before_destroy do
-    raise ActiveRecord::ReadOnlyRecord, '版は削除できません．'
-  end
+  include VersionRecord
 
   belongs_to :post
   belongs_to :parent, class_name: 'Post', optional: true
-  belongs_to :created_by_user, class_name: 'User', optional: true
 
-  enum :event_type, { create: 'create',
-                      update: 'update',
-                      discard: 'discard',
-                      restore: 'restore' }, prefix: true, validate: true
-
-  validates :version_no, presence: true, numericality: { only_integer: true, greater_than: 0 }
-  validates :event_type, presence: true, inclusion: { in: event_types.keys }
   validates :url, presence: true
 
   validate :validate_original_created_range
 
-  scope :chronological, -> { order(:version_no, :id) }
-
   private
 
   def validate_original_created_range

backend/app/models/tag.rb

@@ -8,8 +8,6 @@ class Tag < ApplicationRecord
     ;
   end
 
-  default_scope -> { kept }
-
   has_many :post_tags, inverse_of: :tag
   has_many :active_post_tags, -> { kept }, class_name: 'PostTag', inverse_of: :tag
   has_many :post_tags_with_discarded, -> { with_discarded }, class_name: 'PostTag'
@@ -36,6 +34,9 @@ class Tag < ApplicationRecord
   has_many :deerjikists, dependent: :delete_all
   has_many :materials
 
+  has_many :tag_versions
+  has_many :nico_tag_versions
+
   belongs_to :tag_name
   delegate :wiki_page, to: :tag_name
 
@@ -152,10 +153,11 @@ class Tag < ApplicationRecord
     retry
   end
 
-  def self.merge_tags! target_tag, source_tags
+  def self.merge_tags! target_tag, source_tags, created_by_user: nil
     target_tag => Tag
 
     affected_post_ids = Set.new
+    affected_tag_ids = Set.new
 
     Tag.transaction do
       Array(source_tags).compact.uniq.each do |source_tag|
@@ -166,7 +168,7 @@ class Tag < ApplicationRecord
         source_tag.post_tags.kept.find_each do |source_pt|
           post_id = source_pt.post_id
           affected_post_ids << post_id
-          source_pt.discard_by!(nil)
+          source_pt.discard_by!(created_by_user)
           unless PostTag.kept.exists?(post_id:, tag: target_tag)
             PostTag.create!(post_id:, tag: target_tag)
           end
@@ -179,6 +181,7 @@ class Tag < ApplicationRecord
         end
 
         source_tag.discard!
+        record_tag_discard!(source_tag, current_by_user: nil)
 
         if source_tag.nico?
           source_tag_name.discard!
@@ -186,10 +189,12 @@ class Tag < ApplicationRecord
           source_tag_name.update_columns(canonical_id: target_tag.tag_name_id,
                                          updated_at: Time.current)
         end
+
+        record_tag_version!(target_tag, event_type: :update, created_by_user: nil)
       end
 
       Post.where(id: affected_post_ids.to_a).find_each do |post|
-        PostVersionRecorder.record!(post:, event_type: :update, created_by_user: nil)
+        PostVersionRecorder.record!(post:, event_type: :update, created_by_user:)
       end
 
       # 投稿件数を再集計
@@ -199,6 +204,14 @@ class Tag < ApplicationRecord
     target_tag.reload
   end
 
+  def snapshot_aliases = tag_name.aliases.kept.order(:name).pluck(:name)
+
+  def snapshot_parent_tag_ids = parents.order('id').pluck('id')
+
+  def snapshot_linked_tags
+    linked_tags.joins(:tag_name).order('tag_names.name').pluck('tag_names.name')
+  end
+
   private
 
   def nico_tag_name_must_start_with_nico

backend/app/models/tag_version.rb

@@ -0,0 +1,16 @@
+class TagVersion < ApplicationRecord
+  include VersionRecord
+
+  belongs_to :tag
+
+  enum :category, { deerjikist: 'deerjikist',
+                    meme: 'meme',
+                    character: 'character',
+                    general: 'general',
+                    material: 'material',
+                    meta: 'meta',
+                    nico: 'nico' }, validate: true
+
+  validates :name, presence: true
+  validates :category, presence: true
+end

backend/app/models/version_record.rb

@@ -0,0 +1,19 @@
+module VersionRecord
+  extend ActiveSupport::Concern
+
+  def readonly? = persisted?
+
+  included do
+    belongs_to :created_by_user, class_name: 'User', optional: true
+
+    enum :event_type, { create: 'create',
+                        update: 'update',
+                        discard: 'discard',
+                        restore: 'restore' }, prefix: true, validate: true
+
+    validates :version_no, presence: true, numericality: { only_integer: true, greater_than: 0 }
+    validates :event_type, presence: true
+
+    scope :chronological, -> { order(:version_no, :id) }
+  end
+end