Add emoji reaction validation per account/emoji

app/models/emoji_reaction.rb

@@ -28,6 +28,7 @@ class EmojiReaction < ApplicationRecord
 
   has_one :notification, as: :activity, dependent: :destroy
 
+  validate :status_same_emoji_reaction
   validate :status_emoji_reactions_count
 
   after_create :refresh_cache
@@ -53,6 +54,12 @@ class EmojiReaction < ApplicationRecord
     query
   end
 
+  def status_same_emoji_reaction
+    if status && account && status.emoji_reactions.where(account: account).where(name: name).where(custom_emoji_id: custom_emoji_id).any?
+      raise Mastodon::ValidationError, I18n.t('reactions.errors.duplication')
+    end
+  end
+
   def status_emoji_reactions_count
     if status && account && status.emoji_reactions.where(account: account).count >= EMOJI_REACTION_PER_ACCOUNT_LIMIT
       raise Mastodon::ValidationError, I18n.t('reactions.errors.limit_reached')

config/locales/en.yml

@@ -1423,6 +1423,7 @@ en:
     title: Privacy Policy
   reactions:
     errors:
+      duplication: Cannot react same things
       limit_reached: Limit of different reactions reached
       unrecognized_emoji: is not a recognized emoji
   relationships:

config/locales/ja.yml

@@ -1390,6 +1390,7 @@ ja:
     title: プライバシーポリシー
   reactions:
     errors:
+      duplication: 同じリアクションを複数行おうとしました
       limit_reached: リアクションの種類が上限に達しました
       unrecognized_emoji: は絵文字として認識されていません
   relationships: