Agile Buzz Forum - Ruby on Rails

So part 2 - Ruby on Rails. First - use the packager and install Rails. "What is Rails?" Rails is a wrapper around a bunch of other little frameworks. The core is made up of ActiveRecord and ActionPack. ActiveRecord is a simple O/R mapping pattern. ActionPack implements the web-facing piece, implementing an MVC pattern for the web. The big thing to remember about Rails is this:

Convention over Configuration

One of the results of this is that using Ruby, you don't end up arguing over things like "which db framework, which directory structure...", etc. etc. So the first step - create an ActiveRecord subclass for the first bit of the domain, and then use some Ruby code to create a table for it. The class Chad created has more fields, but you get the idea:

 

class CeateContacts < ActiveRecord::Migration
	def self.up
	       create_table :contacts do | t |
	       t.column :first_name, :string
	       t.column :last_name, :string
		 t.column :created_at, :datetime
	end
end

def self.down
	drop.table :contacts
end

end

Class Contact < ActiveRecord::Base
end

That last bit does the class to table mapping. That's it - by following this convention, we have the mapping. Note that we didn't worry about primary keys, SQL (etc, etc). You can name various columns in ways that will automatically map to the database in intelligent ways.

There's a nice log being kept for you that saves a record of your database interactions; this can be useful for figuring out what SQL is being created, and where you may need to tweak.

Some more code - a controller (the handler for actions on the back end). There would typically be a view here for rendering, but we are just being simple (like my web examples in my screencasts :) )


class ContactsController < ApplicationController
def index
	@contacts = Contact.find(:all)
	render :text => @contacts.inspect
end

Now a new View HTML Page (in its own directory structure spot) to handle the rendering. Like web toolkit (and other web frameworks), there's a way to embed Ruby code in pages


<html>
<body>
	<h1>Contacts!</h1>
	<ul>
	<% @contacts.each do | contact | %>
		<li><%= contact.first_name %><%= contact.last_name %></li>
	<% end %>
	</ul>
</body>
</html>

Simply change the controller to eliminate the specific rendering using inspect. The framework also handles giving you basic forms for editing domain objects based on the Ruby and DB definitions. There are a number of built in things for pagination, number of items per page (etc, etc).

With respect to code generation, Chad finds it to be mostly useful for "getting started" and setting up the initial scaffolding.

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