Rails validation error messages: Displaying only one error message per field

Question

Rails displays all validation error messages associated with a given field. If I have three validates_XXXXX_of :email, and I leave the field blank, I get three

Answer 1

I use this code for Ruby on Rails 3.0 release, which I put in lib/core_ext/rails/active_model/errors.rb:

module ActiveModel
  class Errors
    def full_message_per_field
      messages_per_field = []
      handled_attributes = []

      each do |attribute, messages|
        next if handled_attributes.include? attribute
        messages = Array.wrap(messages)
        next if messages.empty?

        if attribute == :base
          messages_per_field << messages.first
        else
          attr_name = attribute.to_s.gsub('.', '_').humanize
          attr_name = @base.class.human_attribute_name(attribute, :default => attr_name)
          options = { :default => "%{attribute} %{message}", :attribute => attr_name }

          messages_per_field << I18n.t(:"errors.format", options.merge(:message => messages.first))
        end

        handled_attributes << attribute
      end

      messages_per_field
    end
  end
end

This is essentially the same code as ActiveModel::Errors#full_messages, but won't show more than one error per attribute. Be sure to require the file (say, in an initializer) and now you can call @model.errors.full_message_per_field do |message| ...