Merge pull request #34309 from oliverguenther/patch-1

Document `deep_interpolation` parameter for bulk lookups

guides/source/i18n.md

@@ -664,6 +664,26 @@ I18n.t 'activerecord.errors.messages'
 # => {:inclusion=>"is not included in the list", :exclusion=> ... }
 ```
 
+If you want to perform interpolation on a bulk hash of translations, you need to pass `deep_interpolation: true` as a parameter. When you have the following dictionary:
+
+```yaml
+en:
+  welcome:
+    title: "Welcome!"
+    content: "Welcome to the %{app_name}"
+```
+
+then the nested interpolation will be ignored without the setting:
+
+```ruby
+I18n.t 'welcome', app_name: 'book store'
+# => {:title=>"Welcome!", :content=>"Welcome to the %{app_name}"}
+
+I18n.t 'welcome', deep_interpolation: true, app_name: 'book store'
+# => {:title=>"Welcome!", :content=>"Welcome to the book store"}
+```
+
+
 #### "Lazy" Lookup
 
 Rails implements a convenient way to look up the locale inside _views_. When you have the following dictionary: