Alex Vollmer

I stumbled across a little bit of hidden Rails fun last night when I was trying to get the form_for method to stop wrapping error fields with extra div tags. Did you know that? Maybe you never noticed, but when you use the field helper methods, like text_field, password_field, etc, Rails will wrap fields with errors in a <div> with the class 'fieldWithErrors'.

This was causing all sorts of grief for me in some JavaScript I was trying to write. At first I tried to go with the flow and fix my JS, but it got really hacky really fast. So I went on a little source-code spelunking to figure how to make the problem go away.

In actionpack-2.1.0 there is a Proc attached to the ActionView::Base.field_error_proc class attribute. It's not documented in the RDoc, but this is also a writable attribute which means I can shut the damn thing up. Here's what it looks like in the original file, GEM_HOME/actionpack-2.1.0/lib/action_view/helpers/active_record_helper.rb:

require 'cgi'
require 'action_view/helpers/form_helper'

module ActionView
  class Base
    @@field_error_proc = Proc.new{ |html_tag, instance| "<div class=\"fieldWithErrors\">#{html_tag}</div>" }
    cattr_accessor :field_error_proc
  end
  ...
end

My solution was to create a little file in config/initializers named field_errors.rb with this text:

ActionView::Base.field_error_proc = Proc.new do |html_tag, instance|
  html_tag
end

Et voila! Just a simple pass-through with no more fancy-pants markup. Putting stuff like this in separate files in the initializers directory keeps your config and environment files from getting out of hand.

Make View Helpers a Little Less "Helpful" comments

Alex
Vollmer