Fix #4017: Artist tag in upload page should account for aliases

Disallow creating artist entries for aliased tags. Add a fix script to
move existing artist entries for tags that have been aliased.

app/models/artist.rb

@@ -13,7 +13,7 @@ class Artist < ApplicationRecord
   normalize :other_names, :normalize_other_names
   array_attribute :other_names # XXX must come after `normalize :other_names`
 
-  validate :validate_tag_category
+  validate :validate_artist_name
   validates :name, tag_name: true, uniqueness: true
 
   before_save :update_tag_category
@@ -23,8 +23,8 @@ class Artist < ApplicationRecord
   has_many :members, :class_name => "Artist", :foreign_key => "group_name", :primary_key => "name"
   has_many :urls, :dependent => :destroy, :class_name => "ArtistUrl", :autosave => true
   has_many :versions, -> {order("artist_versions.id ASC")}, :class_name => "ArtistVersion"
-  has_one :wiki_page, :foreign_key => "title", :primary_key => "name"
-  has_one :tag_alias, :foreign_key => "antecedent_name", :primary_key => "name"
+  has_one :wiki_page, -> { active }, foreign_key: "title", primary_key: "name"
+  has_one :tag_alias, -> { active }, foreign_key: "antecedent_name", primary_key: "name"
   belongs_to :tag, foreign_key: "name", primary_key: "name", default: -> { Tag.new(name: name, category: Tag.categories.artist) }
 
   scope :banned, -> { where(is_banned: true) }
@@ -155,12 +155,16 @@ class Artist < ApplicationRecord
   end
 
   module TagMethods
-    def validate_tag_category
-      return unless !is_deleted? && name_changed? && tag.present?
+    def validate_artist_name
+      return unless !is_deleted? && name_changed?
 
-      if tag.category_name != "Artist" && !tag.empty?
+      if tag.present? && tag.category_name != "Artist" && !tag.empty?
         errors.add(:name, "'#{name}' is a #{tag.category_name.downcase} tag; artist entries can only be created for artist tags")
       end
+
+      if tag_alias.present?
+        errors.add(:name, "'#{name}' is aliased to '#{tag_alias.consequent_name}'")
+      end
     end
 
     def update_tag_category

script/fixes/098_fix_aliased_artists.rb

@@ -0,0 +1,29 @@
+#!/usr/bin/env ruby
+
+require_relative "base"
+
+# Fix artist entries where the tag was aliased but the URLs weren't moved to
+# the new artist entry.
+with_confirmation do
+  CurrentUser.scoped(User.system, "127.0.0.1") do
+    aliased_artists = Artist.joins(:tag_alias).where.associated(:urls).distinct
+
+    aliased_artists.each do |artist|
+      next if artist.tag.category_name != "Artist"
+      next if artist.tag_alias.consequent_tag.category_name != "Artist"
+
+      old_name = artist.name
+      new_name = artist.tag_alias.consequent_name
+
+      artist.update_attribute(:is_deleted, false) # undelete first so the tag move works
+      TagMover.new(old_name, new_name).move_artist!
+      added_urls = (artist.urls - Artist.find_by_name(new_name).urls).map(&:url)
+
+      puts({
+        old_name: old_name,
+        new_name: new_name,
+        added_urls: added_urls,
+      }.to_json)
+    end
+  end
+end

test/unit/artist_test.rb

@@ -517,6 +517,14 @@ class ArtistTest < ActiveSupport::TestCase
         assert(artist.invalid?)
         assert_match(/'touhou' is a copyright tag/, artist.errors.full_messages.join)
       end
+
+      should "not allow creating artist entries for aliased tags" do
+        tag_alias = create(:tag_alias, antecedent_name: "foo", consequent_name: "bar")
+        artist = build(:artist, name: "foo")
+
+        assert_equal(true, artist.invalid?)
+        assert_match(/'foo' is aliased to 'bar'/, artist.errors.full_messages.join)
+      end
     end
 
     context "when renaming" do