Rails is terrific, but if you're new to web development, I suggest you give Sinatra a try first. Not only is it excellent for building small web apps, but concepts such as routing are also much easier to understand and learn.

Sinatra Framework

Install Sinatra Framework

gem install sinatra

ORM

DataMapper is broken up into the core library, dm-core, various database adapters and a number of optional libraries collectively:

Install everything:

gem install data_mapper

Install things piece by piece:

DataMapper core

gem install dm-core

Constraints

require 'dm-constraints'

Migrations

require 'dm-migrations'

Pick a database adapter:
MySQL

gem install do_mysql

Postgresql

gem install do_postgres

SQLite

gem install dm-sqlite-adapter

Views

sudo gem install Haml

Example File

This file model.rb starts with

require 'rubygems'
require 'dm-core'
#require 'dm-constraints'
require 'dm-migrations'
require 'sinatra'  
require 'sinatra/reloader' if development?

DataMapper::Logger.new($stdout, :debug)
DataMapper.setup(:default, 'mysql://localhost/ruby_shortner')

Reloader

Reloader is great for restarting your computer every time you make a file edit.

 gem install sinatra-contrib

Add this to index.rb

require 'sinatra'
require 'sinatra/reloader' if development?

Resources