From 60c8c63353bf702e9756f12bc59e6aef882277ea Mon Sep 17 00:00:00 2001
From: miteruzo <miteruzo@naver.com>
Date: Thu, 12 Mar 2026 21:41:28 +0900
Subject: [PATCH] #281

---
 .../app/controllers/wiki_pages_controller.rb  |  2 +-
 backend/app/models/my_discard.rb              | 20 +++++++++++++++++++
 backend/app/models/tag.rb                     |  6 +++---
 backend/app/models/tag_name.rb                |  8 ++------
 backend/app/models/wiki_page.rb               |  2 +-
 backend/spec/requests/posts_spec.rb           | 10 ++++++----
 backend/spec/tasks/nico_sync_spec.rb          |  4 ++--
 7 files changed, 35 insertions(+), 17 deletions(-)
 create mode 100644 backend/app/models/my_discard.rb

diff --git a/backend/app/controllers/wiki_pages_controller.rb b/backend/app/controllers/wiki_pages_controller.rb
index 749cf19..dc6c47f 100644
--- a/backend/app/controllers/wiki_pages_controller.rb
+++ b/backend/app/controllers/wiki_pages_controller.rb
@@ -90,7 +90,7 @@ class WikiPagesController < ApplicationController
 
     return head :unprocessable_entity if name.blank? || body.blank?
 
-    tag_name = TagName.find_or_create_by!(name:)
+    tag_name = TagName.find_undiscard_or_create_by!(name:)
     page = WikiPage.new(tag_name:, created_user: current_user, updated_user: current_user)
     if page.save
       message = params[:message].presence
diff --git a/backend/app/models/my_discard.rb b/backend/app/models/my_discard.rb
new file mode 100644
index 0000000..dc4a98d
--- /dev/null
+++ b/backend/app/models/my_discard.rb
@@ -0,0 +1,20 @@
+module MyDiscard
+  extend ActiveSupport::Concern
+
+  included { include Discard::Model }
+
+  class_methods do
+    def find_undiscard_or_create_by! attrs, &block
+      record = with_discarded.find_by(attrs)
+
+      if record&.discarded?
+        record.undiscard!
+        record.update_columns(created_at: record.reload.updated_at)
+      end
+
+      record or create!(attrs, &block)
+    rescue ActiveRecord::RecordNotUnique
+      retry
+    end
+  end
+end
diff --git a/backend/app/models/tag.rb b/backend/app/models/tag.rb
index 9f480cd..a8926c2 100644
--- a/backend/app/models/tag.rb
+++ b/backend/app/models/tag.rb
@@ -1,5 +1,5 @@
 class Tag < ApplicationRecord
-  include Discard::Model
+  include MyDiscard
 
   class NicoTagNormalisationError < ArgumentError
     ;
@@ -134,10 +134,10 @@ class Tag < ApplicationRecord
   end
 
   def self.find_or_create_by_tag_name! name, category:
-    tn = TagName.find_or_create_by!(name: name.to_s.strip)
+    tn = TagName.find_undiscard_or_create_by!(name: name.to_s.strip)
     tn = tn.canonical if tn.canonical_id?
 
-    Tag.find_or_create_by!(tag_name_id: tn.id) do |t|
+    Tag.find_undiscard_or_create_by!(tag_name_id: tn.id) do |t|
       t.category = category
     end
   rescue ActiveRecord::RecordNotUnique
diff --git a/backend/app/models/tag_name.rb b/backend/app/models/tag_name.rb
index c353d2f..b118300 100644
--- a/backend/app/models/tag_name.rb
+++ b/backend/app/models/tag_name.rb
@@ -1,5 +1,5 @@
 class TagName < ApplicationRecord
-  include Discard::Model
+  include MyDiscard
 
   default_scope -> { kept }
 
@@ -27,10 +27,6 @@ class TagName < ApplicationRecord
 
   private
 
-  def sanitise_name
-    self.name = TagNameSanitisationRule.sanitise(name)
-  end
-
   def canonical_must_be_canonical
     if canonical&.canonical_id?
       errors.add :canonical, 'canonical は実体を示す必要があります．'
@@ -50,7 +46,7 @@ class TagName < ApplicationRecord
   end
 
   def name_must_be_sanitised
-    if name != TagNameSanitisationRule.sanitise(name)
+    if name? && name != TagNameSanitisationRule.sanitise(name)
       errors.add :name, '名前に使用できない文字が含まれてゐます．'
     end
   end
diff --git a/backend/app/models/wiki_page.rb b/backend/app/models/wiki_page.rb
index b1d1b02..1573127 100644
--- a/backend/app/models/wiki_page.rb
+++ b/backend/app/models/wiki_page.rb
@@ -2,7 +2,7 @@ require 'set'
 
 
 class WikiPage < ApplicationRecord
-  include Discard::Model
+  include MyDiscard
 
   default_scope -> { kept }
 
diff --git a/backend/spec/requests/posts_spec.rb b/backend/spec/requests/posts_spec.rb
index b2f3e54..ee4fcc5 100644
--- a/backend/spec/requests/posts_spec.rb
+++ b/backend/spec/requests/posts_spec.rb
@@ -525,8 +525,9 @@ RSpec.describe 'Posts API', type: :request do
 
     context "when nico tag already exists in tags" do
       before do
-        Tag.find_or_create_by!(tag_name: TagName.find_or_create_by!(name: 'nico:nico_tag'),
-                               category: :nico)
+        Tag.find_undiscard_or_create_by!(
+            tag_name: TagName.find_undiscard_or_create_by!(name: 'nico:nico_tag'),
+            category: :nico)
       end
 
       it 'return 400' do
@@ -610,8 +611,9 @@ RSpec.describe 'Posts API', type: :request do
 
     context "when nico tag already exists in tags" do
       before do
-        Tag.find_or_create_by!(tag_name: TagName.find_or_create_by!(name: 'nico:nico_tag'),
-                               category: :nico)
+        Tag.find_undiscard_or_create_by!(
+            tag_name: TagName.find_undiscard_or_create_by!(name: 'nico:nico_tag'),
+            category: :nico)
       end
 
       it 'return 400' do
diff --git a/backend/spec/tasks/nico_sync_spec.rb b/backend/spec/tasks/nico_sync_spec.rb
index daa243e..d4f0e09 100644
--- a/backend/spec/tasks/nico_sync_spec.rb
+++ b/backend/spec/tasks/nico_sync_spec.rb
@@ -8,8 +8,8 @@ RSpec.describe "nico:sync" do
   end
 
   def create_tag!(name, category:)
-    tn = TagName.find_or_create_by!(name: name.to_s.strip)
-    Tag.find_or_create_by!(tag_name_id: tn.id) { |t| t.category = category }
+    tn = TagName.find_undiscard_or_create_by!(name: name.to_s.strip)
+    Tag.find_undiscard_or_create_by!(tag_name_id: tn.id) { |t| t.category = category }
   end
 
   def link_nico_to_tag!(nico_tag, tag)