Why I am a DataMapper convert (it makes BDD happy)

T here’s lots of buzz around DataMapper right now, especially among the #merb crowd. I haven’t had any major issues with ActiveRecord, so I haven’t needed to look at a new ORM…but I like to play with new things, so last night I really gave the DM a try.

I’m a complete convert, if for no other reason that the awesome way automigrations play along with BDD.

First, tell your spec_helper to use automigrations:

DataMapper::Base.auto_migrate!

This will cause your database tables to be dropped and re-created so use with caution.

Next, let’s spec some behavior:

it "should have a username field" do
  @person.username = "jjames"
  @person.username.should == "jjames"
end

And see what autotest says:

....F.....

1)
NoMethodError in 'Person should have a username field'
undefined method `username=' for #<person:0x13f720c>
./spec/models/person_spec.rb:38:

Finished in 0.049775 seconds

10 examples, 1 failure

Cool, that’s what we expected. Now, with ActiveRecord, to get to green, we’d need to create a migration and run it. With DataMapper, we stay in our model:

class Person < DataMapper::Base
  property :username, :string
end

And autotest says…

..........

Finished in 0.040584 seconds

10 examples, 0 failures

Now, is this perfect? Not yet. DM has a good amount of work still. There’s some smart folks working on it, and I bet it will be pretty sweet in a few more weeks.

But, man…that’s just awesome.

Merb 0.4.0 released

A bout 6 months ago or so I looked at Merb as a potential replacement for small apps that I didn’t want to use Rails for. It seemed cool, but pretty rough, and I didn’t have a good reason to use it.

Fast forward to the Ruby Hoedown in August. Ezra Zygmuntowicz, Merb’s creator, gave a talk about Merb. I saw some things I had missed, that were really exciting.

• HTTP Status Codes handled via Exceptions
• Emphasis on speed and small code base
• Closer match between the framework and the flavor of the HTTP spec

I checked out the code.

I played around.

I got excited about how I could keep most of the code in my head at the same time.

I submitted some patches.

Ez gave me commit.

I wrote some sample controllers and specs.

I wrote a replacement for `respond_to` that I think is pretty awesome.

I flew to Charlotte for about 18 hours for a Merb hack session at RubyConf.

Tonight, Ez pushed Merb 0.4.0 to Rubyforge.

It’s just crazy to think how quickly I’ve gotten involved in this project, how excited I am about this 0.4.0 release, and how much I’m looking forward to using this framework to build some cool apps.

If you’re interested in Merb, pop over to http://merbivore.com or join us on IRC in #merb. We’re pretty sure you’ll like it.