Paul Barry

Customizing Generators in Rails 3

January 13, 2010

As you probably already know, Rails 3 is just around the corner. There are some pretty nice features being added and one of them is the ability to customize the way the generators work. I personally prefer Haml over ERB, RSpec over Test::Unit and Factory Girl over Fixtures. So let’s see how we can configure a Rails 3 app to do that.

First, follow Yehuda’s instructions on how to create a Rails 3 app. Next, you have to tell Rails that you want to use Haml, RSpec and Factory Girl. First, add this somewhere in the Gemfile:

gem "haml"

only :test do
  gem "rspec"
  gem "rspec-rails"
  gem "factory_girl"

Then, re-run the bundler and initialize the Haml plugin:

$ gem bundle
$ bin/haml --rails .

Finally, you have to install the custom generators for the frameworks that you want to use. I found a repo on github that already had RSpec, so I forked it and added Haml and Factory Girl. Clone the repo into the lib/generators directory of your app:

$ git clone git:// lib/generators

Now, in the config/application.rb file in your app, near the bottom there is a section related to config.generators. Put this in that section:

config.generators do |g|
  g.template_engine :haml
  g.test_framework :rspec, :fixture => true, :views => false
  g.fixture_replacement :factory_girl, :dir => "spec/factories"

Here is where we reap the benefits of the modularity in Rails 3. What this says is that we want to use Haml as the template enging, we want to use RSpec as the test framework and we want to generate fixtures with our generated specs, but we don’t want to generate view specs and that instead of fixtures, we actually want to use factory girl and we want the factories to be put into spec/factories. Whew! So does this all work?

$ script/generate rspec:install
$ script/generate scaffold person name:string dob:date age:integer male:boolean bio:text

At this point you should see that Rails has generated what we want, which is scaffolding that uses Haml for the views, RSpec for the tests and Factory Girl for the fixtures. Run the migrations, start the server and open the browser http://localhost:3000/people to see your scaffolding in action.

Now if you try to actually run rake spec, you’ll get an error, at least I do. I’m not sure that RSpec 1.X is going to ever work with Rails 3. I think the intent is for RSpec 2 to be compatible with Rails 3, so keep an eye out for that.

The Edge of Innovation

April 11, 2008

If you are a programmer that deals with web applications and you keep up with the latest trends, then there is no doubt you will at least have heard of Ruby on Rails. You might be at the level where you have read about Ruby on Rails and played with it a bit, but you really haven’t immersed yourself the Ruby/Rails way. Maybe you know how to build web applications with Java, .Net or PHP, and you think “Rails is nice, but there’s nothing Rails can do that you can’t do in X”.

If you are in this camp, it may be because you aren’t willing to adapt your ways to Rails. To really understand the benefits of Rails, you have to not only learn Rails, but learn the best practices followed by good Rails programmers, like Skinny Controller, Fat Model, REST and Behavior Driven Development. You don’t see the true benefit of Ruby until you start to fully embrace concepts like these. The only way to learn concepts like these is to read blogs, listen to podcasts, talk to other Ruby programmers at work, user groups and conferences and most importantly, you have to actually write code that reflects what you have learned. You must put aside your preconceived notions about what is right and what is wrong and surrender to the flow. You must unlearn what you have learned.

So if you haven’t experienced this transformation first hand yet, and someone asks you “What is the biggest advantage to Ruby on Rails”, I would be willing to bet your answer would be productivity. This is the way I think many people involved with technology, who don’t fully grasp the Rails Way, perceive Rails. They believe, with some cynicism, that because of the dynamic nature of Rails, you can develop applications faster. They’ll also probably say the downside is that Rails can’t scale.

But anyway, I’m hear to say that productivity is the most over-rated benefit of Rails. The real advantage to Rails is that it is written in Ruby, which is a very powerful language that will change the way you think about programming. It’s funny, I’ve thought to myself a number of times about how interesting it is that Ruby fundamentally changes the way you think about programming and that “Thinking in Ruby” would probably be a great book. But ironically, Bruce Eckel, the author of the “Thinking in…” line of programming books, seems to be happy with Python and not willing to give Ruby a chance. Who knows, that article is a few years old now, so maybe he’s changed his attitude towards Ruby since then. I know mine has.

It’s hard to quantify the advantage that “Thinking in Ruby” brings. The simplest way I can state it is that you will look at problems differently and come up with better solutions, solutions you may not have thought of if you were programming in other languages. The way I support this claim is by looking at some of the web application development innovations that have come out of the Ruby community.

The first is Rails itself. Rails has been copied, ported, attempted to be ported or talked about being ported to almost every other mainstream language you could think of, including Groovy, PHP, JavaScript, Perl, Java and .Net. This phenomenon is unique to Rails, I can’t think of any other web application framework that can say that. If not the whole framework itself, parts of it such as convention over configuration, migrations and embracing REST have influenced the way web application development is done in almost every language.

Another example is HAML. HAML is a truly new and different take of the problem of generating HTML from a combination of dynamic code and HTML. It is a new idea and it has been ported to PHP, Python, and .Net. Whenever you have a framework or library that is being ported to other languages, it shows that the framework being ported contains new and good ideas about programming. In other words, it is a contribution to the paradigm of web development and a clear sign that the original language that the framework was implemented is at the edge of innovation.

Another example is Behavior Driven Development. This example is even more interesting because the idea originally started in Java with the JBehave framework. Even though the idea for behavior driven development started with Java, the idea didn’t really take off until it was implemented in RSpec. They are fairly similar in terms of syntax. Here’s an example from the JBehave website:

public class CheeseBehaviour extends UsingJMock {
    public void shouldRequireTheUseOfMocks() {
        // given
        Mock cheese = new Mock(Cheese.class);
        Sheep sheep = new Sheep((Cheese)cheese.proxy());


        // when

        // then

and here it is converted to RSpec:

describe Sheep do
  before do
    @cheese = mock(Cheese)
    @sheep = mock(Sheep, :cheese => @cheese)
  it "should squelch when it eats cheese" do

For whatever reason, JBehave really never took hold in the Java community, but RSpec has in the Ruby community. RSpec has been ported to .Net, PHP and Groovy. All of those projects describe their code as a port of RSpec, not JBehave. Again it is Ruby influencing the wider web application development community.

Post World War II, the center of the art world was New York City and it was there that the modern art movemement was born. New York was where innovation in the art world was happening. In that time period if you wanted to be a serious artist, you had to go to New York to experience the movement first hand. Today, I believe the Ruby community is leading the way in innovative techniques for web application development. There is certainly innovation happening in other languages like Python, Smalltalk and Erlang as well, but I don’t think any one other language/community is doing as much as Ruby. As far as I can tell, languages like Java, .Net and PHP are doing nothing to innovate web application development. They are simply lagging behind, playing catch up and trying to figure out how implement new features pioneered in the Ruby community and others as closely as possible, given the limitations of the language. So if you are a web developer, I suggest you ask yourself this question. Are the languages and frameworks you are working with leading others to come up with new ideas? Are the languages and frameworks that you are working helping you come up with new ideas? If not, embrace Ruby and someday you will discover an elegant solution to a problem, one that you may not have without Ruby.

A language that doesn’t affect the way you think about programming is not worth knowing. – Alan Perlis

Posted in Technology | Topics Javascript, Java, Ruby, .Net, PHP, RSpec, Python, Rails, HAML