MongoDB - Getting started, Couch, and MongoMapper

A presentation made to SDRuby on MongoDb. I describe how to get started, using mongomapper, and also a little bit about couchdb.

Link to video presentation: http://sdruby.org/podcast/72

Transcript

1. MongoDB Getting started, Couch, and MongoMapper
2. Who am I? • Scott Motte / 25 / Perris, CA • mid-level rubyist that prefers merb • spitfiresky.com • twitter.com/spitfiresky • github.com/scottmotte • scott@spitfiresky.com
3. Leopard Install (0.9.7) • mkdir -p /data/db • wget http://downloads.mongodb.org/osx/mongodb- osx-i386-0.9.7.tgz • sudo tar xvzf mongodb-osx-i386-0.9.7.tgz -C /usr/local • sudo cp -R /usr/local/mongodb-osx-i386-0.9.7/bin/ /usr/ local/bin
4. Linux Install (0.9.7) • mkdir -p /data/db • wget http://downloads.mongodb.org/linux/mongodb- linux-x86_64-0.9.6.tgz • sudo tar -zxvf mongodb-linux-x86_64-0.9.7.tgz -C /usr/ local • sudo chmod 755 -R /usr/local/mongodb-linux- x86_64-0.9.7 • sudo cp -R /usr/local/mongodb-linux-x86_64-0.9.7/bin/* / usr/local/bin
5. Running it • sudo mongod run & • mongo (mysql-like command line) • use bookstore_development • db.books.save({ title: "Ender's Game", description: 'zero gravity and mind games' }) • db.books.findOne()
6. Mongo or Couch Mongodb (C++) Couchdb (Erlang) drivers REST bson, document, schema-free json, document, schema-free Dynamic queries, indexing map/reduce gridfs (needs an apache/nginx module) attachments RAM http cache Good at the web, faster development time Good at the web, slower development time Update in place (good for high update rates) MVCC (fault tolerant, but requires compacting) master-master replication 50s kid indy kid *http://www.mongodb.org/display/DOCS/Comparing+Mongo+DB+and+Couch+DB
7. Mongodb orms Ruby Python mongo-ruby-driver sudo gem install mongodb-mongo sudo gem install mongodb-mongo_ext (c extension) mongo-python-driver easy_install pymongo (c extension auto- installed) active-record-adapter http://github.com/-mongodb/activerecord-mongo-adapter autumn http://autumn-orm.org/ mongorecord http://github.com/mongodb/mongo-activerecord-ruby mongo-mapper http://github.com/jeffjenkins/mongo-mapper mongomapper http://github.com/jnunemaker/mongomapper
8. MongoMapper sudo gem install mongomapper config.gem 'jnunemaker-mongomapper' #rails dependency 'jnunemaker-mongomapper' #merb
9. Model class Book include MongoMapper::Document key :title, String key :description, String end
10. Controller class Books < Application def index @books = Book.all display @books end def show(id) @book = Book.find(id) raise NotFound unless @book display @book end ...
11. Validations class Book include MongoMapper::Document key :title, String key :description, String validates_presence_of :title #validates_numericality_of #validates_length_of #validates_format_of #more end *http://github.com/jnunemaker/validatable
12. Callbacks *http://api.rubyonrails.org/classes/ActiveSupport/Callbacks.html class Book .. key :description, String before_save :append_signature def append_signature self.description << " ~Corner Bookstore" end #after_save #before_validation end
13. Relationships class Book include MongoMapper::Document key :title, String key :description, String has_many :reviews end class Review include MongoMapper::Document key :author, String key :review, String belongs_to :book end
14. Relationships cont. Finding @book = Book.first @reviews = @book.reviews Displaying @reviews.each do |review| review.author end @reviews[0] # return first review Be careful @user.tweets.size #slow Tweet.count(:user_id => @user.id) #fast
15. Embedded Documents class Review include MongoMapper::EmbeddedDocument key :uuid, String, :default => XGen::Mongo::Driver::ObjectID.new key :author, String key :review, String key :created_at, Time, :default => Time.now.utc before_validation do self.uuid = XGen::Mongo::Driver::ObjectID.new end end *http://groups.google.com/group/mongomapper/browse_thread/thread/178b8c5105ebedd8
16. Embedded Docs cont. class Reviews < Application .. def create(review) @flight = Flight.find(params['flight_id']) @review = Review.new(review) if @review.valid? && @flight.reviews << @review && @flight.save redirect '/wherever’' :message => {:notice => "Review made"} else message[:error] = "Review fail" render :new end end end # in router.rb resources :flights, :identify => :id do resources :reviews, :identify => :uuid end # /flights/:flight_id/comments/new
17. Additional info • created_at and updated_at are included automatically by MongoMapper • _id cannot currently be set with MongoMapper like it can in Couchrest • cannot currently do @doc[‘custom_field’] like in couchrest. • indexing: @doc.ensure_index :login
18. Conclusion Mongodb is a great trade off of speed, features, and schema-less freedom, and it now has its developer friendly orm - mongomapper. Strongly consider using it in a web app you otherwise by default would use mysql. Then put together your models and use script/server or bin/merb -i to test your performance improvements. ~ Scott Motte