mini_captcha is a minimalistic captcha plugin for rails projects, based on some code developed for a friend’s website.
developing another captcha plugin (there are a few other plugins out there) was inspired by the spirit of minimalism:

• not to store images in the db
• not to keep images with any of the models that might need captcha protection when creating instances
• keep images only as long as needed (serve once, delete)

HOWTO

To install and integrate to your rails website, follow these steps:

1. install RMagick and Digest — if not yet installed
2. install mini_captcha:
   

   
   
   script/plugin install git@github.com:srejbi/mini_captcha.git
   
   

3. add the following lines to your application controller:
   

   
   
   
   require 'vendor/plugins/mini_captcha/lib/mini_captcha'
   include MiniCaptcha::ControllerHelpers
   
   
   

4. add a map to the MiniCaptcha controller for the MiniCaptcha image display
   

   
   
   
   map.mini_captcha '/mini_captcha/:action', :controller => 'mini_captcha', :action => 'show_image'
   
   
   

5. add a div like this to any view you want to protect with MiniCaptcha from spam:
   

   
   
   
     ... (your page & form)...
     <div class="..."><%= show_mini_captcha  %> </div>
     ... (your page) ....
   
   
   

6. update the processing controller similarly to the following block:
   

   
   
   
    if @form.valid?    your original validation
          if mini_captcha_valid?  extend it with checking the MiniCaptchaChallenge
            do whatever...
            flash[:notice] = 'Your form input was correct.'
            redirect as you wish
          else                     belongs to your new validation of MiniCaptchaChallenge (failure branch)
            flash[:error] = 'Failed MiniCaptcha Challenge.'
            punish the 'bot, piss off the user (just kidding ;))
          end                      end of yout new block for MiniCaptchaChallenge failure
        end
   
   
   

7. enjoy getting less spam, more real comments :-)

Credits: thanks to milkfarm for specs, ideas, and actual updates on the code.

for more details and updates, visit the project page on GitHub