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Every Rails page has footnotes that gives information about your application and links back to your editor
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Rails Footnotes

Rails footnotes 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 3.2+ support, if you want to use footnotes with Rails 2.3 you should use this branch:

Installing Rails Footnotes is very easy.

Rails 3.2.x/4.x

gem 'rails-footnotes', '>= 4.0.0', '<5'

After you install RailsFootnotes and add it to your Gemfile, you need to run the generator:

rails generate rails_footnotes:install

This will create an initializer with default config and some examples.


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' }

Editors links

If you are not using Textmate as text editor, MacVim and Sublime Text 2 are also compatible.


In the rails-footnotes initializer do :

f.prefix = 'mvim://open?url=file://%s&line=%d&column=%d'

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.

Take note that the order in which the file name (%s), line number (%d) and column number (%d) appears is important. We assume that they appear in that order. “foo://line=%d&file=%s” (%d precedes %s) would throw out an error.

Sublime Text 2

  1. Keep the Textmate prefix, f.prefix = 'txmt://open?url=file://%s&line=%d&column=%d'

  2. Install subl-handler

  3. Open subl-handler. Go to preferences (SublHandler > Preferences), and point “Path to subl” to your installed instance. (EG, /Applications/Sublime Text Note: do not escape the whitespaces, subl-handler accounts for those.

  4. Install RCDefault. It's OSX 10.2, but it works.

  5. Go to RCDefaultApp (OS System Preferences > DefaultApps). Go to URL section, select “tmxt” extension, and set default applicaiton to “SublHandler”.

Footnotes Display Options

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:

f.no_style = true

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

f.multiple_notes = true

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

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

Creating your own notes

Creating 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 the 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, add in your initializer:

f.notes += [:current_user]

Display of the notes

By default the notes will be showed at the bottom of your page (appended just before </body>). If you'd like these notes on a different place (perhaps for aesthetical reasons) you can edit one of your views and add:

<div id="footnotes_holder"></div>

at an appropriate place, your notes will now appear inside div#footnotes_holder


Bugs and Feedback

If you discover any bugs, please open an issue. If you just want to give some positive feedback or drop a line, that's fine too!

Version 4.x

Starting from version 4.0, Adren Siami is the maintainer of this plugin.

Version 3.x

This plugin was maintained until version 3.6 by José Valim

Copyright © 2009 José Valim (

Until version 4.0, Roman Babenko maintained this plugin.

Version 2.0

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

Copyright © 2006 InquiryLabs, Inc.

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