I want to implement the following logic of translating Action message:

If source (second parameter passed to $t -- mainPage in the example bellow) is specified it then should try to get a translation from currentLocale.key.source path. If source key (mainPage) was not found or it is null I want to show the key itself ('Action') to a user.

Messages structure:

{
 'by': {
      'Action': {
         'menu': 'Дзеянне',
         'mainPage': 'Аперацыя'
      }
   }
}

mainPage.vue

{{ $t('Action', 'mainPage') }}

One could say that this is the same to $t('Action.mainPage') but in case of undefined translation it will show 'Action.mainPage' which is a no go for me.

I was trying to achieve the same with named-formatting. There is a potential but doesn't seem like a good option as it looks more as hack rather than a solution.

My guess is that $t should be overridden to implement this, but I couldn't figure out how.