== Replacing ActiveRecord with DataMapper in a Rails application

Here is a walk through of the steps I used to create this app:

Pre:  
Install the following gems:
do_mysql (or do_postgres or do_sqlite3)
dm-core
data_mapper
fastthread
json
rspec

1) Generate rails framework

2) Edit config/environment.rb.  Add line:
  config.frameworks -= [ :active_record ]

3) Load DataMapper gem.  Edit config/environment.rb  Add lines:
  config.gem "do_mysql" 
  config.gem "dm-core"

3.1) Make sure your gems are up to date by running "sudo rake gems:install"

4) Configure database.yml

5) Create configuration file for datamapper config/initializers/datamapper.rb

6)  Generate model
script/generate dm_model book amount:float date:date name:string description:text --skip-migration

Two ways to migrate models:

A) migration 1, :create_articles do
 2   up do
 3     create_table :articles do
 4       column :id, Integer, :serial => true, :nullable? => false
 5       column :title, String
 6       column :body, "TEXT"
 7     end
 8   end
 9 
10   down do
11     drop_table :articles
12   end
13 end


B) Properties in your class file & DataMapper.auto_migrate!

NOTE:  I used A) and ran a datamapper migration.  

7) Create migration for initial table:
7.1) Add config.gem "dm-migrations" to config/environment.rb
7.2) Create a migration file (no script/migrate exists!) == Only one line needed!
7.3) Create a new rake task in namespace "dm" to accomodate migrations
   
8)  script/generate controller books index show new create delete
   
9) Create database
   mysqladmin -u root -p create dm2_dev --socket /var/run/mysqld/mysqld.sock

10) Run migration 
    rake dm:migrate 
    
11) Add content to files