translate
translate(keys, options = {})
public
Delegates to I18n#translate but also performs two additional functions. First, it’ll catch MissingTranslationData exceptions and turn them into inline spans that contains the missing key, such that you can see in a view what is missing where.
Second, it’ll scope the key by the current partial if the key starts with a period. So if you call translate(".foo") from the people/index.html.erb template, you’ll actually be calling I18n.translate("people.index.foo"). This makes it less repetitive to translate many keys within the same partials and gives you a simple framework for scoping them consistently. If you don’t prepend the key with a period, nothing is converted.
Default fallback
You can specifly :default option which is useful when the translation is not found. For example:
t(:this_translation_doesnt_exist, :default => 'Ooops!') # => Ooops!
Or even any number of “fallbacks” - the first not nil is returned:
t(:missing, :default => [:missing_too, :existing, 'Sad panda']) # => :existing translation
Good introduction to Rails I18n is http://guides.rubyonrails.org/i18n.html