This walkthrough will take you through the steps to get a Merb app up and running with a protected resource. It assumes you are running Merb 0.9.9 or greater with the Merb Stack (merb-core, merb-more, and datamapper).

Lets start at the beginning and create an app
$ merb-gen app authentication_app
$ cd authentication_app

By default merb-gen app will create a user model for you in app/models/user.rb. The model is there, but we still need to create the table in the database and add a user to authenticate with. Lets do that now.
$ rake db:auto_migrate

To create our first user we can drop into Merb’s irb console mode with merb -i. Like Rails’ script/console, merb -i gives you access to your models and other classes.

$ merb -i
u = User.new
u.login = 'joe'
u.password = u.password_confirmation = 'password'
u.save
exit

In order to test authentication we need something to protect. Any controller would work, but lets create a resource.
$ merb-gen resource secret

We will need to add a route to the resource also
# router.rb
Merb::Router.prepare do
resources :secrets
...
end

To protect a controller with authentication we can use the before filter ensure_authenticated
# app/controllers/secrets.rb
class Secrets < Application
before :ensure_authenticated
...
end

Everything should now be setup in our app. Lets give it a run through.

First you need to start you merb server. Make sure you are in your merb app’s root directory.
$ merb

Now you can test access to your resource is denied before authentication.

http://localhost:4000/secrets

Login in and try to access the recourse again.

http://localhost:4000/login

http://localhost:4000/secrets

You should now be able to access the resource. Awesome.

Merb Overheard follows the planet-type aggregation sites similar to Planet Ruby on Rails and Planet PHP. It follows a list of relevant blogs and aggregates those articles into one place.

When I first decided to build Merb Overheard I was originally planning on writing it in Merb of course, but I starting to realize all the battles I was going to have ahead of me. Caching and pagination of no database objects were not something I really wanted to deal with, so I decided to try something different. Instead of trying to shove the aggregator into a framework, why not just build out the pages statically?

Merb Overhead is just a plain old ruby script that gets ran every 30 minutes from a cron task. Each time it is ran, all the pages are recreated using Erubius. This script, weighing in at a whopping 8 lines of code, implements two classes in a library I wrote called Pluto. The class for the feed aggregator is only 30 lines. The class to generate the view is only 45 lines.

The code is released on Github so go nuts creating collecting all your Furby Fan Club sites or whatever else strikes your fancy.

Turns out there is a bug is merb-cache (part of merb-more) that is causing the problem. It’s patched in wycatz’ branch so pull down his latest version and get blogging!

Special thanks to my buddy Peter to figuring this one out.