What is a "resource" in Rails?

Question

Dumb question but I have some lingering confusion of what, exactly, a "resource" is in Rails. The term is used everywhere but I get a funny feeling it might be being used rather loosely. It's referenced in the model, the controller and, quite literally, in routes.rb.

Is it the specific route? For example, map.resources maps the 7 RESTful "resources". So an example of one resource would be the call to, say, the index action of a particular class's controller?!?

Is it a reference to the whole page/object being retrieved? or perhaps, more narrowly, a database table? or the row being retreived?

Is it something else?

Anyway, hopefully someone can set me straight...

Answer 1

Any object that you want users to be able to access via URI and perform CRUD (or some subset thereof) operations on can be thought of as a resource. In the Rails sense, it is generally a database table which is represented by a model, and acted on through a controller.

For example, you might have a User resource (with a users table in your DB). This is represented by a User model, is mapped to users_controller with map.resources :users (which then generates routes like /users (a collection of User resources) and /users/1 (a specific User resource).

You act upon those resources by using the appropriate HTTP method when making calls to those resources. POST to the resource collection (/users) creates a new record; GET retrieves a list of resources (/users) or a specific user (/users/1). PUT updates a specific user (/users/1/), and DELETE destroys that user. The URLs are the same, but the result (and controller action) may be different based on the HTTP verb. The idea, though is that /users/1 always means "I'm interacting with the User that has ID #1", regardless of the action.

Answer 2

Here's a good article discussing how most developers think that "Resource" is synonomous with the database table, the argument, I guess, being that mapping to the resource is mapping the controller to that database table (or, with ActiveResource, to another REST url).

Basically, I think a "resource" is "persisted data." map.resources maps the 7 RESTful actions to a particular suite of persisted data.

But I haven't thought about it too much in depth. Good question!