to_param, the Best Method Ever

If you want to create vanity URLs, and who doesn’t, then to_param is the method for you. In fact it is my personal favorite method in Ruby on Rails, narrowly edging out time_ago_in_words.

On Twitter, the link for a users profile would look something like https://twitter.com/charlesmassry which would call the to_param method on the user model, if in fact Twitter used Rails. There is one difficulty in this, users can’t have their usernames as certain reserved words, like sign-out, or search. This can be remedied in two ways, one, you can check validation on the usernames, or two, you can make it a part of the user resources, /users/charlesmassry. The second way is much easier because you would have to check validation on every reserved route if you chose the first one, however, I think the first way looks a lot cleaner.

app/models/user.rb

class User < ActiveRecord::Base
  ...
  validates_exclusion_of :username, in: %w{ sign-out search }
  ...
end

As for the to_param method itself, you would just redefine it in your model.

app/models/user.rb

class User < ActiveRecord::Base
  ...
  def to_param
    username
  end
  ...
end

By default, it is just an instance method that essentially returns a string with the id of that resource to give you routes like https://twitter.com/1 as opposed to the username at the end.