+TIP: Declaring a resource will automatically generate the +*_path+ functions above. The short syntax expects such a function to exist based on the model of the object it is acting on. To declare a model as a resource, add the model to the resources list in the routes file +config/routes.rb+ like so: <pre>map.resources :articles</pre> Declaring a resource has a number of side-affects. See "Rails Routing From the Outside In":http://guides.rubyonrails.org/routing.html#restful-routing-the-rails-default for more information on setting up and using resources.
Notice how the short-style +form_for+ invocation is conveniently the same, regardless of the record being new or existing. Record identification is smart enough to figure out if the record is new by asking +record.new_record?+. It also selects the correct path to submit to and the name based on the class of the object.
Rails will also automatically set the +class+ and +id+ of the form appropriately: a form creating an article would have +id+ and +class+ +new_article+. If you were editing the article with id 23, the +class+ would be set to +edit_article+ and the id to +edit_article_23+. These attributes will be omitted for brevity in the rest of this guide.