【Rails】devise_token_authから送るメールの件名を変えたい！

<h2>devise_token_authから送るメールの件名を変えた”い！</h2>
ユーザー作成時やパスワードリセットなどのdevice_token_authの機能を使用した際に、Email送信がされるものがありますね。

そのメールの件名がバリバリ英語なので、自分のアプリに合うような最高な件名に変えた"い！

その方法について簡潔に記していきます。

<h2>変更方法</h2>
方法はいたってシンプル！

config/locales/devise.en.ymlを開いて、自分が変えたいところのsubjectを変えるだけ！

```yml:devise.en.yml
# Additional translations at https://github.com/heartcombo/devise/wiki/I18n

en:
  devise:
    confirmations:
      confirmed: "Your email address has been successfully confirmed."
      send_instructions: "You will receive an email with instructions for how to confirm your email address in a few minutes."
      send_paranoid_instructions: "If your email address exists in our database, you will receive an email with instructions for how to confirm your email address in a few minutes."
    failure:
      already_authenticated: "You are already signed in."
      inactive: "Your account is not activated yet."
      invalid: "Invalid %{authentication_keys} or password."
      locked: "Your account is locked."
      last_attempt: "You have one more attempt before your account is locked."
      not_found_in_database: "Invalid %{authentication_keys} or password."
      timeout: "Your session expired. Please sign in again to continue."
      unauthenticated: "You need to sign in or sign up before continuing."
      unconfirmed: "You have to confirm your email address before continuing."
    mailer:
      confirmation_instructions:
        subject: "Confirmation instructions"
      reset_password_instructions:
        subject: "パスワードリセットのタイトルを変えるならここ！"
      unlock_instructions:
        subject: "Unlock instructions"
      email_changed:
        subject: "Email Changed"
      password_change:
        subject: "Password Changed"
    omniauth_callbacks:
      failure: "Could not authenticate you from %{kind} because \"%{reason}\"."
      success: "Successfully authenticated from %{kind} account."
    passwords:
      no_token: "You can't access this page without coming from a password reset email. If you do come from a password reset email, please make sure you used the full URL provided."
      send_instructions: "You will receive an email with instructions on how to reset your password in a few minutes."
      send_paranoid_instructions: "If your email address exists in our database, you will receive a password recovery link at your email address in a few minutes."
      updated: "Your password has been changed successfully. You are now signed in."
      updated_not_active: "Your password has been changed successfully."
    registrations:
      destroyed: "Bye! Your account has been successfully cancelled. We hope to see you again soon."
      signed_up: "Welcome! You have signed up successfully."
      signed_up_but_inactive: "You have signed up successfully. However, we could not sign you in because your account is not yet activated."
      signed_up_but_locked: "You have signed up successfully. However, we could not sign you in because your account is locked."
      signed_up_but_unconfirmed: "A message with a confirmation link has been sent to your email address. Please follow the link to activate your account."
      update_needs_confirmation: "You updated your account successfully, but we need to verify your new email address. Please check your email and follow the confirmation link to confirm your new email address."
      updated: "Your account has been updated successfully."
      updated_but_not_signed_in: "Your account has been updated successfully, but since your password was changed, you need to sign in again."
    sessions:
      signed_in: "Signed in successfully."
      signed_out: "Signed out successfully."
      already_signed_out: "Signed out successfully."
    unlocks:
      send_instructions: "You will receive an email with instructions for how to unlock your account in a few minutes."
      send_paranoid_instructions: "If your account exists, you will receive an email with instructions for how to unlock it in a few minutes."
      unlocked: "Your account has been unlocked successfully. Please sign in to continue."
  errors:
    messages:
      already_confirmed: "was already confirmed, please try signing in"
      confirmation_period_expired: "needs to be confirmed within %{period}, please request a new one"
      expired: "has expired, please request a new one"
      not_found: "not found"
      not_locked: "was not locked"
      not_saved:
        one: "1 error prohibited this %{resource} from being saved:"
        other: "%{count} errors prohibited this %{resource} from being saved:"

```


<h2>参考</h2>

https://devise-token-auth.gitbook.io/devise-token-auth/config/devise