Nice Text Captcha by Neil Smith

About

This generates text-based CATPCHAs that are “nice”, by my own personal subjective definition!

Questions are purposely simple, and examples would include:

  • How many letters are there in the word ‘White’?

  • In the word “tiger”, what is the letter in the 5th position?

  • How many animals are in the words: “cat”, “orange”, and “dolphin”?

  • What is ‘four’ + “nine”?

Implementation

You call a method in your view which both generates a random question, and places the possible answers into a flash[] object, stored in a SHA2 hash.

(It’s stored in a flash, as Rails handles ageing the data after a request - if we used the session, it would hang around for the duration of the session.)

Then, in your controller action, you call a method which extracts the answers from the flash, and injects them into your model.

A validation method on the model finally checks the answer against the hashed possible answers, and pushes an error onto the base of your model if the answer doesn’t match.

For numerical answers (“What is ‘two’ plus ‘three’?”), both numbers (“3”) and words (“three”) are accepted.

Requirements

Tested against Rails 2.3 - currently untested against Rails 3. ‘linguistics’ gem for turning numbers into words and ordinals. ‘Digest/SHA2’ for hashing the possible answers.

Instructions

In your model, you need to add some validation:

class Thing < ActiveRecord::Base

validate :check_nice_text_captcha

end

In your controller, you need to add a call to populate the answers from the data in the session:

class ThingsController < ActiveRecord::Base

def create

@thing = Thing.new(params) # as normal validate_nice_text_captcha_for(@thing) end end

Finally, in your view, you need to render the question by calling nice_text_captcha, and give the user a text box for their answer:

<% form_for(@thing) do |f| %>

<!-- normal form elements here -->

<%= f.nice_text_captcha %><br /> <%= f.text_field :nice_text_captcha %><br /> <!– probably a submit button here –>

<% end %>