—€ this.

app/controllers/user_controller.rb

@@ -8,7 +8,7 @@ class UserController < ApplicationController
   end
 
   def update
-    params.permit(:display_name)
+    params.require(:display_name)
     current_user.display_name = params[:display_name]
     current_user.save!
     redirect_to edit_user_profile_path

app/views/user/edit.html.haml

@@ -1,4 +1,8 @@
 .container.j2-page
   = render 'settings_tabs'
   .col-md-9.col-xs-12.col-sm-9
-    %i TODO
+    = bootstrap_form_for(update_user_profile_path, method: "patch") do |f|
+      
+      = f.text_field :display_name, label: "Your name"
+      
+      = f.submit