#20

backend/app/models/post.rb

@@ -9,8 +9,8 @@ class Post < ApplicationRecord
   has_many :post_tags_with_discarded, -> { with_discarded }, class_name: 'PostTag'
   has_many :tags, through: :active_post_tags
 
-  has_many :user_post_views, dependent: :destroy
-  has_many :post_similarities, dependent: :destroy
+  has_many :user_post_views, dependent: :delete_all
+  has_many :post_similarities, dependent: :delete_all
 
   has_one_attached :thumbnail
 

backend/app/models/tag.rb

@@ -22,6 +22,8 @@ class Tag < ApplicationRecord
            class_name: 'TagImplication', foreign_key: :tag_id, dependent: :destroy
   has_many :parents, through: :reversed_tag_implications, source: :parent_tag
 
+  has_many :tag_similarities, dependent: :delete_all
+
   belongs_to :tag_name
   delegate :name, to: :tag_name, allow_nil: true
   validates :tag_name, presence: true
@@ -72,7 +74,7 @@ class Tag < ApplicationRecord
 
     tags = tag_names.map do |name|
       pf, cat = CATEGORY_PREFIXES.find { |p, _| name.start_with?(p) } || ['', nil]
-      name = name.delete_prefix(pf)
+      name = TagName.canonicalise(name.delete_prefix(pf)).first
       find_or_create_by_tag_name!(name, category: (cat || :general)).tap do |tag|
         if cat && tag.category != cat
           tag.update!(category: cat)
@@ -109,6 +111,8 @@ class Tag < ApplicationRecord
 
   def self.find_or_create_by_tag_name! name, category:
     tn = TagName.find_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|
       t.category = category
     end
@@ -127,7 +131,7 @@ class Tag < ApplicationRecord
   end
 
   def tag_name_must_be_canonical
-    if tag_name&.canonical_id
+    if tag_name&.canonical_id?
       errors.add :tag_name, 'tag_names へは実体を示す必要があります．'
     end
   end

backend/app/models/tag_name.rb

@@ -9,6 +9,16 @@ class TagName < ApplicationRecord
 
   validate :canonical_must_be_canonical
   validate :alias_name_must_not_have_prefix
+  validate :canonical_must_not_be_present_with_tag_or_wiki_page
+
+  def self.canonicalise names
+    names = Array(names).map { |n| n.to_s.strip }.reject(&:blank?)
+    return [] if names.blank?
+
+    tns = TagName.includes(:canonical).where(name: names).index_by(&:name)
+
+    names.map { |name| tns[name]&.canonical&.name || name }.uniq
+  end
 
   private
 
@@ -23,4 +33,10 @@ class TagName < ApplicationRecord
       errors.add :name, 'エーリアス名にプレフィクスを含むことはできません．'
     end
   end
+
+  def canonical_must_not_be_present_with_tag_or_wiki_page
+    if canonical_id? && (tag || wiki_page)
+      errors.add :canonical, 'タグもしくは Wiki の参照がある名前はエーリアスになれません．'
+    end
+  end
 end