Display email in session info area when user has no username

app/controllers/application_controller.rb

@@ -19,7 +19,7 @@ class ApplicationController < ActionController::Base
   end
 
   def decorated_current_user
-    current_user && current_user.decorate
+    current_user && CurrentUserDecorator.new(current_user)
   end
 
   def ensure_authenticated!

app/decorators/current_user_decorator.rb

@@ -0,0 +1,7 @@
+class CurrentUserDecorator < UserDecorator
+
+  def display_name
+    model.username || model.email
+  end
+
+end

app/decorators/user_decorator.rb

@@ -1,6 +1,10 @@
 class UserDecorator < ApplicationDecorator
   include AvatarHelper
 
+  def display_name
+    model.username || model.temporary_username || "user:#{id}"
+  end
+
   def link
     wrap_with_link(display_name)
   end
@@ -35,8 +39,4 @@ class UserDecorator < ApplicationDecorator
     end
   end
 
-  def display_name
-    username || temporary_username || "user:#{id}"
-  end
-
 end

app/views/layouts/_header.html.slim

@@ -22,7 +22,7 @@ header.navbar.navbar-default[role="navigation"]
           li.dropdown
             a.dropdown-toggle[href="#" data-toggle="dropdown"]
               = current_user.avatar_image_tag
-              = current_user.username
+              = current_user.display_name
               b.caret
             ul.dropdown-menu
               li