#281

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

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

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

backend/app/models/wiki_page.rb

@@ -2,7 +2,7 @@ require 'set'
 
 
 class WikiPage < ApplicationRecord
-  include Discard::Model
+  include MyDiscard
 
   default_scope -> { kept }