How does Stack Overflow generate its SEO-friendly URLs?

Question

What is a good complete regular expression or some other process that would take the title:

How do you change a title to be part of the URL like Stack

Answer 1

Assuming that your model class has a title attribute, you can simply override the to_param method within the model, like this:

def to_param
  title.downcase.gsub(/ /, '-')
end

This Railscast episode has all the details. You can also ensure that the title only contains valid characters using this:

validates_format_of :title, :with => /^[a-z0-9-]+$/,
                    :message => 'can only contain letters, numbers and hyphens'