module ActiveRecord::Integration::ClassMethods

User.find(params[:id]).id # => 123
params[:id] # => "123-fancy-pants"

suitable for passing to +find+. In a controller, for example:
Because the generated param begins with the record's +id+, it is

user_path(user) # => "/users/125-david"
user.id # => 125
user = User.find_by(name: 'David HeinemeierHansson')

is truncated word by word.
Values longer than 20 characters will be truncated. The value

user_path(user) # => "/users/123-fancy-pants"
user.id # => 123
user = User.find_by(name: 'Fancy Pants')

end
to_param :name
class User < ActiveRecord::Base

responds to +to_s+.
using +method_name+, which can be any attribute or method that
Defines your model's +to_param+ method to generate "pretty" URLs

def to_param(method_name = nil)
  if method_name.nil?
    super()
  else
    define_method :to_param do
      if (default = super()) &&
           (result = send(method_name).to_s).present? &&
             (param = result.squish.truncate(20, separator: /\s/, omission: nil).parameterize).present?
        "#{default}-#{param}"
      else
        default
      end
    end
  end
end