Search Engine Friendly Rails Routing

In the model, we can override the default parameters with the to_param method. We call the parameterize method on the object’s name attribute, which converts “My Pet Turtle!!!” to “my-pet-turtle”. The end result is a url that is formatted like: /123-my-pet-turtle.

def to_param
  "#{id}-#{name.parameterize}"
end

That’s it, there’s no other code that needs to be changed in the application. Your existing controller methods that use Model.find(params[:id]) will still work because they will only extract the initial id number. This is decent, but it would still be nice to have the URL completely free of the ID number. Let’s start over to make this happen.

I call this the hardish way because it’s relatively complicated compared to the easy way, but it’s still quite easy overall. We’re going to create a new permalink attribute for the Post model that will serve as our URL.

$ rails g migration AddPermalinkToPost permalink:string

$ rake db:migrate

In the model, we are going to use an ActiveRecord callback to set the permalink before the record is created. First, we need to define a generate_permalink method, which uses a Post object's title and converts it to a url friendly format. Then we override the to_param method and set it equal to the object's permalink attribute.

It is important to only run the callback on the create action, otherwise the permalink will change if the title attribute is updated. If Google has already indexed that URL, it will direct visitors to a 404 error page.

models/post.rb

before_validation :generate_permalink, on: :create

def generate_permalink
  self.permalink = self.title.parameterize
end

def to_param
  permalink
end

Now that the ID is totally stripped from the URL, we need to tell rails to search for a different parameter. In the controller, we will need to use the find_by_permalink helper method. Note, the params hash will still have a key of “id”, such as {:id => “my-pet-turtle” }

controllers/posts_controller.rb

def set_post
  @post = Post.find_by_permalink(params[:id])
end

There is one problem with this implementation — duplicate permalinks. We could just run a uniqueness validation, but this would be confusing for end users, as it would raise a validation error for a seemingly valid title. If any duplicates exist, we can refactor our generate permalink method to check for duplicates, then append a number to the end of the URL based on the number of existing duplicates. For example, if there are three other Posts titled “My Post”, you would end up with the following permalinks: “my-post”, “my-post–2”, and “my-post–3”.

The method below defines a pattern variable, then searches the database for other rows that contain that same pattern. It will count the matching patterns, then append the count to the end of of permalink.

def generate_permalink
  pattern = self.title.parameterize

  duplicates = Post.where("permalink LIKE ?", "#{pattern}%")

  unless duplicates.empty?
    self.permalink = "#{pattern}-#{duplicates.count+1}"
  else
    self.permalink = pattern
  end

end

There are several gems to help you build SEO friendly URLs. I am not recommending a particular gem, but wanted to include them for completeness.

has_permalink

friendly_id