= Introduction

This is a Ruby driver for the 10gen Mongo DB. For more information about
Mongo, see http://www.mongodb.org.

Note: this driver is still alpha quality. The API will change, as *may* the
data saved to the database (especially primary key values). Do *_not_* use
this for any production data yet.

Start by reading the XGen::Mongo::Driver::Mongo and XGen::Mongo::Driver::DB
documentation, then move on to XGen::Mongo::Driver::Collection and
XGen::Mongo::Driver::Cursor.

A quick code sample:

  require 'mongo'

  include XGen::Mongo::Driver

  db = Mongo.new('localhost').db('sample-db')
  coll = db.collection('test')

  coll.clear
  3.times { |i| coll.insert({'a' => i+1}) }
  puts "There are #{coll.count()} records. Here they are:"
  coll.find().each { |doc| puts doc.inspect }

= Installation

Install the "mongo" gem by typing

  $ sudo gem install mongo

The source code is available at http://github.com/jimm/mongo-ruby-driver. You
can either clone the git repository or download a tarball or zip file. Once
you have the source, you can use it from wherever you downloaded it or you can
install it as a gem from the source by typing

  $ rake gem:install


= Demo

You can see and run the examples if you've downloaded the source. Mongo must
be running, of course.

  $ ruby examples/simple.rb

See also the test code, especially tests/test_db_api.rb.


= Notes

== String Encoding

The BSON ("Binary JSON") format used to communicate with Mongo requires that
strings be UTF-8 (http://en.wikipedia.org/wiki/UTF-8).

Ruby 1.9 has built-in character encoding support. All strings sent to Mongo
and received from Mongo are converted to UTF-8 when necessary, and strings
read from Mongo will have their character encodings set to UTF-8.

When used with Ruby 1.8, the bytes in each string are written to and read from
Mongo as-is. If the string is ASCII all is well, because ASCII is a subset of
UTF-8. If the string is not ASCII then it may not be a well-formed UTF-8 string.

= Testing

If you have the source code, you can run the tests.

  $ rake test

The tests assume that the Mongo database is running on the default port.

The project mongo-qa (http://github.com/mongodb/mongo-qa) contains many more
Mongo driver tests that are language independent. To run thoses tests as part
of the "rake test" task, run

  $ rake mongo_qa
  $ rake test

The mongo_qa task uses the "git clone" command to make a copy of that project
in a directory named mongo-qa. If the directory already exists, then the
mongo_qa task uses "git pull" to updated the code that's there. The Ruby
driver tests will then use some of the data files from that project when it
runs BSON tests. You can delete this directory at any time if you don't want
to run those tests any more.

Additionally, the script bin/validate is used by the mongo-qa project's
validator script.


= Documentation

This documentation is available online at http://mongo.rubyforge.org. You can
generate the documentation if you have the source by typing

  $ rake rdoc

Then open the file html/index.html.


= Release Notes

See the git log comments.


= To Do

* Add group_by. Need to figure out how we are going to send functions. The
  current thinking is that Mongo will allow a subset of JavaScript (which we
  would have to send as a string), but this is still under discussion.

* Tests for update and repsert.

* Add a way to specify a collection of databases on startup (a simple array of
  IP address/port numbers, perhaps, or a hash or something). The driver would
  then find the master and, on each subsequent command, ask that machine if it
  is the master before proceeding.

* Introduce optional per-database and per-collection PKInjector.

* More tests.

== Optimizations

* Only update message sizes once, not after every write of a value. This will
  require an explicit call to update_message_length in each message subclass.

* ensure_index commands should be cached to prevent excessive communication
  with the database. (Or, the driver user should be informed that ensure_index
  is not a lightweight operation for the particular driver.)


= Credits

Adrian Madrid, aemadrid@gmail.com
* bin/mongo_console
* examples/benchmarks.rb
* examples/irb.rb
* Modifications to examples/simple.rb
* Found plenty of bugs and missing features.
* Ruby 1.9 support.
* Gem support.
* Many other code suggestions and improvements.


= License

Copyright (C) 2008-2009 10gen Inc.

This program is free software: you can redistribute it and/or modify it under
the terms of the GNU Affero General Public License, version 3, as published by
the Free Software Foundation.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
details.

See http://www.gnu.org/licenses for a copy of the GNU Affero General Public
License.