nested_attributes を使った際にエラーメッセージを正しく表示させる

errors_i18n.rb

# config/initializers/errors_i18n.rb
ActiveModel::Errors.module_eval do

  def full_messages
    full_messages = []

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

      if attribute == :base
        messages.each {|m| full_messages << m }
      else
        # attr_name = attribute.to_s.gsub('.', '_').humanize
        attr_name = convert_name(attribute.to_s) 
        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.each do |m|
          full_messages << I18n.t(:"errors.format", options.merge(:message => m))
        end
      end
    end

    full_messages
  end
  
  def to_text
    output_string = ""
    full_messages.each{|attr,msg| output_string << "#{attr} - #{msg}\n" }
    output_string
  end
  

  def convert_name(name)
    default = nil
    if name =~ /(.+)\.(.+)/
      base_name = $1
      attribute = $2
      # base = ActiveSupport::Dependencies.constantize(base_name.camelize)
      base = ActiveSupport::Dependencies.constantize(base_name.camelize.singularize)
      if (base.respond_to? :model_name)
        default = "#{base.model_name.human} #{base.human_attribute_name(attribute.to_sym, :default => attribute.humanize)}"
      end
    end
    default 
  end  
  
end