how can i connect to a mongodb from Ruby code?

how can i connect to a mongodb from Ruby code ?

Firstly, you have to install MongoDb gem:

gem install mongo

Then run code:

require 'rubygems'  # not necessary for Ruby 1.9
require 'mongo'
db = Mongo::Connection.new.db("mydb") # OR
db = Mongo::Connection.new("localhost").db("mydb") # OR
db = Mongo::Connection.new("localhost", 27017).db("mydb")

Kir's answer is appropriate if you are working only with Ruby. But if you are developing a Rails app, you likely will want to connect to MongoDB with an ORM such as:

• Mongoid
• MongoMapper

Using an ORM will give you the functionality Rails developers are familiar with in ActiveRecord. See a list of MongoDB Clients on http://ruby-toolbox.com/.

• http://www.mongodb.org/display/DOCS/Ruby+Language+Center
• http://api.mongodb.org/ruby/current/file.TUTORIAL.html

Short version: install the Mongo gem, then db = Mongo::Connection.new.db("mydb")