Use another I18n key in an I18n interpolation
This is actually a pretty common question, but the short answer is no, this isn't possible unfortunately :(
Currently I struggle for it... And finally I create a custom yaml type.
in init section.
Psych.add_builtin_type('i18n') { |_type, value| ->(_key, _options) do value.gsub(/%\{([\w.]+)\}/) do |match| key = $1.to_sym if I18n.exists?(key) I18n.t(key) else match end end end}I18n.reload!in en.yml
en: my_var: Foo my_message: !!i18n "This is a message where I'd like to interpolate I18n's %{my_var}"!!i18n apply custom builtin type.
As you said, maybe it is not a so straight solution to call twice from the view to the translation
<%= t("my_message", my_var: t("my_var") ) %>but gives you the flexibility to call with a variable
<%= t("my_message", my_var: t("my_#{$item[:slug]}") ) %>