form_for error messages in Ruby on Rails

Question

What is the preferred way to display validation error messages using form_for in Rails 4?

<%= form_for @post do |f| %>
  ...
<% end %&g         


        

Answer 1

I know this isn't exactly what was asked, but if you are using the simple_form gem, which I recommend, you can use f.error_notification which takes :message as an option.

= f.error_notification message: form_errors_for(your_object)

I use a method pretty similar to Wes's answer; form_errors_for inside application_helper.rb

def form_errors_for_base(object)
  if object.errors.messages[:base].present?
    object.errors.messages[:base].join(",\n") + "."
  else
    nil
  end
end