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Rails Footnotes

If you are developing in Rails you should know the plugin! It displays footnotes in your application for easy debugging, such as sessions, request parameters, cookies, filter chain, routes, queries, etc.

Even more, it contains links to open files directly in your editor including your backtrace lines.


NOTE: Since this branch aims Rails 3 support, if you want to use it with Rails 2.3 you should check this branch:

Install Rails Footnotes is very easy.

Rails 3.x

gem 'rails-footnotes', '>= 3.7', :group => :development

Rails 2.x

In RAILS_ROOT/config/environments/development.rb (yes, you want it only in development):

gem "rails-footnotes", '< 3.7.0', :group => :development


For version greater then 3.7.0

If you want to add alternate logic to enable or disable footnotes, add something like this to config/initializers/footnotes.rb:

if defined?(Footnotes) && Rails.env.development?! # first of all

  # ... other init code


Footnotes.setup do |config|
  config.before {|controller, filter| filter.notes = =~ /Message/ && \
    controller.action_name == 'index' ? [:assigns] : []}
  config.before {|controller, filter| filter.notes |= [:params] if =~ /Profile/ && \
    controller.action_name == 'edit' }

If you are not using Textmate as text editor, in your environment.rb or in an initializer do:

Footnotes::Filter.prefix = 'mvim://open?url=file://%s&amp;line=%d&amp;column=%d'

for MacVim

Where you are going to choose a prefix compatible with your text editor. The %s is replaced by the name of the file, the first %d is replaced by the line number and the second %d is replaced by the column.

By default, footnotes are appended at the end of the page with default stylesheet. If you want to change their position, you can define a div with id “footnotes_holder” or define your own stylesheet by turning footnotes stylesheet off:

Footnotes::Filter.no_style = true

Another option is to allow multiple notes to be opened at the same time:

Footnotes::Filter.multiple_notes = true

If you have New Relic RPM installed, you may want to turn off query explains (explains can slows things down)

Footnotes::Notes::QueriesNote.sql_explain = false

Finally, you can control which notes you want to show. The default are:

Footnotes::Filter.notes = [:session, :cookies, :params, :filters, :routes, :env, :queries, :log, :general]

Creating your own notes

Create your notes to integrate with Footnotes is easy.

  1. Create a Footnotes::Notes::YourExampleNote class

  2. Implement the necessary methods (check abstract_note.rb file in lib/notes)

  3. Append your example note in Footnotes::Filter.notes array (usually at the end of your environment file or in an initializer):

For example, to create a note that shows info about the user logged in your application you just have to do:

module Footnotes
  module Notes
    class CurrentUserNote < AbstractNote
      # This method always receives a controller
      def initialize(controller)
        @current_user = controller.instance_variable_get("@current_user")

      # Returns the title that represents this note.
      def title
        "Current user: #{}"

      # This Note is only valid if we actually found an user
      # If it's not valid, it won't be displayed
      def valid?

      # The fieldset content
      def content

Then put in your environment:

Footnotes::Filter.notes += [:current_user]


Bugs and Feedback

If you discover any bugs, please send an e-mail to If you just want to give some positive feedback or drop a line, that's fine too!

Version 3.x

This plugin was maintained until version 3.6 by José Valim

Copyright © 2009 José Valim (

Version 2.0

This plugin was created and maintained until version 2.0 by Duane Johnson:

Copyright © 2006 InquiryLabs, Inc.

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