translate
translate(key, options = {})
public
Delegates to I18n#translate but also performs three additional functions.
First, it’ll pass the :rescue_format => :html option to I18n so that any thrown MissingTranslation messages will be turned into inline spans that
* have a "translation-missing" class set, * contain the missing key as a title attribute and * a titleized version of the last key segment as a text.
E.g. the value returned for a missing translation key :“blog.post.title” will be <span class=“translation_missing” title=“translation missing: en.blog.post.title”>Title</span>. This way your views will display rather reasonable strings but it will still be easy to spot missing translations.
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.
Third, it’ll mark the translation as safe HTML if the key has the suffix “_html” or the last element of the key is the word “html”. For example, calling translate(“footer_html”) or translate(“footer.html”) will return a safe HTML string that won’t be escaped by other HTML helper methods. This naming convention helps to identify translations that include HTML tags so that you know what kind of output to expect when you call translate in a template.
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