Question

In some book, it is recommended that to_param is changed to

class Story < ActiveRecord::Base

  def to_param
    "#{id}-#{name.gsub(/\W/, '-').downcase}"
  end

end

so that the URL is

http://www.mysite.com/stories/1-css-technique-blog

instead of

http://www.mysite.com/stories/1

so that the URL is more search engine friendly.

So probably to_param() doesn’t need to be used by other parts of Rails that changing it may have any side effect? Or maybe the only purpose is to construct a URL for linking?

Another thing is, won’t it require to limit the URL size to be less than 2k in length — will it choke IE if it is more than 2k or maybe the part more than 2k is just ignored by IE and so the URL still works. It might be better to be limited to 30 or 40 characters or something that will make the URL not exceedingly long.

Also, the ri doc of to_param:

       class User < ActiveRecord::Base
         def to_param  # overridden
           name
         end
       end

if to_param is changed like that, then the link actually won’t work, as

http://www.mysite.com/stories/1-css-technique-blog

will work, but

http://www.mysite.com/stories/css-technique-blog

will not work as the ID is missing. Are there other ways to change the to_param method?

Update: on second thought, maybe

http://www.mysite.com/stories/css-technique-blog

won’t work well if there are many webpages with similar title. but then

http://www.mysite.com/user/johnchan

will work. Will it be params[:id] being “johnchan”? So then we will use

user = User.find_by_login_name(params[:id])

to get the user. So it just depends on how we use the param on the URL.

C:\ror>ri ActiveRecord::Base#to_param
-------------------------------------------- ActiveRecord::Base#to_param
     to_param()
------------------------------------------------------------------------
     Returns a String, which Action Pack uses for constructing an URL to
     this object. The default implementation returns this record's id as
     a String, or nil if this record's unsaved.

     For example, suppose that you have a User model, and that you have
     a +map.resources :users+ route. Normally, +user_path+ will
     construct a path with the user object's 'id' in it:

       user = User.find_by_name('Phusion')
       user_path(user)  # => "/users/1"

     You can override +to_param+ in your model to make +user_path+
     construct a path using the user's name instead of the user's id:

       class User < ActiveRecord::Base
         def to_param  # overridden
           name
         end
       end

       user = User.find_by_name('Phusion')
       user_path(user)  # => "/users/Phusion"

Answer 1

If you want to make your url more search engine friendly, you can use the friendly_id gem which makes exactly what you want. Is the easier way I’ve found to generate search engine friendly permalinks.