to_param

Defines your model’s to_param method to generate “pretty” URLs using method_name, which can be any attribute or method that responds to to_s.

class User < ActiveRecord::Base
  to_param :name
end

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

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

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

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

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