Ruby on Rails
ORMQL Plugin

ORMQL (Object Relational Mapping Query Language) is a very simple query language to retrieve ActiveRecord objects from a database. It consists in the standard SQL where the FORM part is eliminated and column names are substituted by ActiveRecord attributes names, including nested associations. It is not necessary to learn any new language because ORMQL is a simple substitution of relevant parts in the query string and the result is sent to database as normal query.

ORMQL Rails plugin adds two methods to ActiveRecord::Base class, find_by_ormql and count_by_ormql

The advantage of using find_by_ormql over normal finder find is that the eager loading is unlimited and automatic.

Simple example

Having these models:

class Author < ActiveRecord::Base
  belongs_to :country
  has_many   :articles
  has_many   :comments
end

class Country < ActiveRecord::Base
  has_many   :authors
end

class Article < ActiveRecord::Base
  belongs_to :author, :class_name => 'User'
  has_many   :comments
end

class Comment < ActiveRecord::Base
  belongs_to :article
  belongs_to :author, :class_name => 'User'
end

Now I can make this query:

for user in User.find_by_ormql('SELECT nick, country.name, articles.comments.title WHERE surname=? ORDER BY country.name', 'Llorach')
  puts "#{user.nick} is from #{user.country.name} and has written by example the comment #{article.comment.title}" 
end

Download

The latest version of ORMQL Rails plugin can be found at http://rubyforge.org/projects/ormql/

See also Plugins