![config/initializers/mongo.rb
# Read in the config info
mongo_cfg = YAML.load(
IO.read("#{RAILS_ROOT}/config/mongodb.yml")
)[RAILS_ENV]
# Create the connection from mongodb.yml
args = [mongo_cfg['host'],mongo_cfg['port']].compact
MongoMapper.connection =
Mongo::Connection.new(*conn_args)
# Pick the Mongo database
db_cfg =
Rails.configuration.database_configuration[RAILS_ENV]
MongoMapper.database =
mongo_cfg['database'] || db_cfg['database']](https://image.slidesharecdn.com/mongodbday-100328123513-phpapp01/85/Using-MongoDB-and-a-Relational-Database-at-MongoDB-Day-37-320.jpg)
![Usage
# Set any preferences you like
user = User.find_by_login('thatguy')
user.preferences[:foreground] = '#FF0000'
user.preferences[:foo] = 'bar'
user.save
# Later on, you can do this
user = User.find_by_login('thatguy')
user.preferences[:foreground] #returns '#FF0000'](https://image.slidesharecdn.com/mongodbday-100328123513-phpapp01/85/Using-MongoDB-and-a-Relational-Database-at-MongoDB-Day-41-320.jpg)
![Skip expandos, use delegate
class Post < ActiveRecord::Base
expando_config do
delegate :tags
end
end
p = Post.find(1)
p.tags = ['foo','bar']
p.save
# Find any Post with the tag "foo"
Post.expando_all(:conditions=>{'tags'=>'foo'})](https://image.slidesharecdn.com/mongodbday-100328123513-phpapp01/85/Using-MongoDB-and-a-Relational-Database-at-MongoDB-Day-45-320.jpg)
Using MongoDB and a Relational Database at MongoDB Day
- 1. Building Good Relations Using MongoDB and a relational database in your apps
- 2. Hayes Davis @hayesdavis CheapTweet.com
- 3. If you’ve already got an app
- 4. You probably already have a database
- 5. It’s probably relational http://www.mbari.org/ssds/ReferenceDocuments/RDB_ER.gif
- 6. It’s probably gotten a little bit big http://www.neonlite.ca/archives/images/big%20cat.jpg
- 7. Or maybe it’s gotten huge http://www.fahad.com/pics/liger.jpg
- 8. And it’s probably pretty complicated http://www.mazes.org.uk/i/101005m.gif
- 9. Or maybe really complicated http://tommilsom.com/wp-content/files/france/maze.jpg
- 10. Which makes it harder to change http://twitter.com/dacort/status/11023722831
- 11. But, you’re not going to throw all that out http://blog.makezine.com/284163191_6f09179853_o.jpg
- 12. So let’s make NoSQL and SQL live in harmony http://curiousanimals.net/wp-content/uploads/2008/03/cat-and-dog-sleep.jpg
- 13. But first...
- 14. Do you even need to?
- 15. We all want to play with shiny new toys http://actionfan.files.wordpress.com/2009/07/voltron_metallic-vinyl-edit.jpg
- 16. But sometimes that’s not the best plan http://www.pwn3d.us/wp-content/uploads/2006/11/voltron_1.jpg
- 17. So, give yourself a test
- 18. #1 Is my data relational?
- 19. #1 Are my data relational?
- 20. #2 Do my data access patterns lend themselves to denormaliation?
- 21. #3 Do I expect a lot of schema change?
- 22. #4 Can I drop ACID? (Atomicity, Consistency, Isolation, Durability)
- 23. #5 Do I want to support a new piece of infrastructure?
- 24. If you answered yes to any of these questions...
- 25. ... at least for parts of your app...
- 26. ... then MongoDB might be right for you http://www.rankopedia.com/CandidatePix/25781.gif
- 28. Utilities and supporting tools
- 29. Logging & analysis http://sbadrinath.files.wordpress.com/2009/03/different26rqcu3.jpg
- 30. We built Parrot http://filmfanatic.org/reviews/wp-content/uploads/2008/01/anfscd-parrot.png
- 31. Isolated subsystems http://themarkvolta.files.wordpress.com/2009/01/lost-map.jpg
- 32. Comments might be a good choice http://www.readwriteweb.com/archives/facebook_wants_to_be_your_one_true_login.php
- 33. Getting practical (in Rails, at least)
- 34. Using MongoMapper and ActiveRecord
- 35. Getting set up
- 36. config/mongodb.yml development: host: 127.0.0.1 test: host: 127.0.0.1 production: host: mongo-server.local
- 37. config/initializers/mongo.rb # Read in the config info mongo_cfg = YAML.load( IO.read("#{RAILS_ROOT}/config/mongodb.yml") )[RAILS_ENV] # Create the connection from mongodb.yml args = [mongo_cfg['host'],mongo_cfg['port']].compact MongoMapper.connection = Mongo::Connection.new(*conn_args) # Pick the Mongo database db_cfg = Rails.configuration.database_configuration[RAILS_ENV] MongoMapper.database = mongo_cfg['database'] || db_cfg['database']
- 38. Mixing your MM with your AR http://i.treehugger.com/images/2007/10/24/frankenstein-jj-001.jpg
- 39. app/models/ preferences.rb class Preferences include MongoMapper::Document key :user_id, Integer end
- 40. apps/models/user.rb class User < ActiveRecord::Base after_save :save_prefs def preferences @preferences ||= Preferences.find_or_create_by_user_id(id) end private def save_prefs @preferences.save if @preferences end end
- 41. Usage # Set any preferences you like user = User.find_by_login('thatguy') user.preferences[:foreground] = '#FF0000' user.preferences[:foo] = 'bar' user.save # Later on, you can do this user = User.find_by_login('thatguy') user.preferences[:foreground] #returns '#FF0000'
- 43. active-expando (very, very alpha)
- 44. Any attribute, any time # Grab a user user = User.find(1) # Now set an attribute that didn't exist before user.expandos.foreground = '#FF0000' # foreground is saved in Mongo user.save # Find any users with a red foreground color users = User.expando_all( :conditions=>{:foreground=>'#FF0000'} )
- 45. Skip expandos, use delegate class Post < ActiveRecord::Base expando_config do delegate :tags end end p = Post.find(1) p.tags = ['foo','bar'] p.save # Find any Post with the tag "foo" Post.expando_all(:conditions=>{'tags'=>'foo'})
- 46. It’s a rails plugin
- 48. Other issues
- 49. Where we’re going we don’t need migrations (or do we?) http://www.gordtep.com/files/2009/08/bttf2.jpg
- 50. Flexibility is great (until it bites you)
- 51. A general word of caution
- 52. MongoDB is a moving target
- 53. So are the tools
- 54. There will be bugs http://nitishkrishna.files.wordpress.com/2009/07/2007_there_will_be_blood_013.jpg
- 55. So, be ready to upgrade
- 56. Questions?