Fix #3363: Prevent setting tags to invalid categories.

app/logical/tag_category.rb

@@ -45,6 +45,10 @@ class TagCategory
       @@categories ||= Danbooru.config.full_tag_config_info.keys
     end
 
+    def category_ids
+      @@categories ||= canonical_mapping.values
+    end
+
     def short_name_list
       @@short_name_list ||= short_name_mapping.keys
     end
@@ -75,4 +79,4 @@ class TagCategory
   extend Mappings
   extend Lists
   extend Regexes
-end
+end

app/models/tag.rb

@@ -12,6 +12,7 @@ class Tag < ApplicationRecord
   has_many :consequent_implications, lambda {active}, :class_name => "TagImplication", :foreign_key => "consequent_name", :primary_key => "name"
 
   validates :name, uniqueness: true, tag_name: true, on: :create
+  validates_inclusion_of :category, in: TagCategory.category_ids
 
   module ApiMethods
     def to_legacy_json

test/unit/tag_test.rb

@@ -119,6 +119,10 @@ class TagTest < ActiveSupport::TestCase
       tag.update_category_cache_for_all
       assert_equal(Tag.categories.copyright, Cache.get("tc:#{Cache.hash(tag.name)}"))
     end
+
+    context "not be settable to an invalid category" do
+      should validate_inclusion_of(:category).in_array(TagCategory.category_ids)
+    end
   end
 
   context "A tag parser" do