多言語化の基盤作り (#55) (#421)

Reviewed-on: #421
Co-authored-by: miteruzo <miteruzo@naver.com>

backend/app/services/post_metadata_fetcher.rb

@@ -47,9 +47,9 @@ class PostMetadataFetcher
 
     existing_tags =
         Tag
-        .joins(:tag_name)
-        .where(tag_names: { name: names })
-        .index_by(&:name)
+        .joins(:tag_names)
+        .where(tag_names: { language_code: 'ja', primary_flg: true, name: names })
+        .index_by { _1.name('ja') }
 
     names.map { |name|
       tag = existing_tags[name]