An example using ActiveRecord to connect to a WordPress database

database.yml

development:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  database: rails_proj_development
  pool: 5
  username: rp_dev
  password: wootwoot
  host: localhost

wp_development:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  database: wpblog_dev
  pool: 5
  username: wp_user
  password: hackable
  host: localhost

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  database: rails_proj_test
  pool: 5
  username: rp_test
  password: wootwoot
  host: localhost

wp_test:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  database: wpblog_test
  pool: 5
  username: wp_user
  password: hackable
  host: localhost

production:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  database: rails_proj_production
  pool: 5
  username: rp_prod
  password: wootwoot
  host: localhost

wp_production:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  database: wpblog_prod
  pool: 5
  username: wp_user
  password: hackable
  host: localhost

post.rb

##
# An example using ActiveRecord to connect to a WordPress database
#
module WordPress
  class Post < ActiveRecord::Base
    # tell active record to use another database connection
    establish_connection  "wp_#{Rails.env}"

    # set the table name
    set_table_name        "wp_posts"

    # normalize/sanitize some attributes to make things more railsy
    alias_attribute       "author",         "post_author"
    alias_attribute       "posted_on",      "post_date"
    alias_attribute       "posted_on_gmt",  "post_date_gmt"
    alias_attribute       "content",        "post_content"
    alias_attribute       "title",          "post_title"
    alias_attribute       "excerpt",        "post_excerpt"
    alias_attribute       "status",         "post_status"

    # add any virtual attributes to abstract gory details
    def published?
      self.status == "publish"
    end
  end
end