Getting started with MongoDB and Scala

Open Source BridgeJune 27, 2012Sean Sullivan

Gilt Groupe

Gilt Portland

http://twitter.com/tinyrobots/status/217675630962163713

Jobs @ Gilt Portland

• QA engineering

• Backend engineering

• Frontend engineering

#scala #java #html5 #javascript#ruby

open source @ Gilt

• MongoDB

• Using Mongo and Scala together

• MongoDB at Gilt

“MongoDB is a document-oriented database management system designed for performance, horizontal scalability, high availability, and advanced queryability”

source: http://docs.mongodb.org/manual/about/

http://www.mongodb.org

https://github.com/mongodb/mongo

Licensing

Database: GNU AGPL v3.0

Drivers: Apache License 2.0

source: http://www.mongodb.org/display/DOCS/Licensing

Getting started

http://www.mongodb.org/downloads

http://www.mongodb.org/downloads

MongoDB concepts

MySQL MongoDBdatabase database

table collectionindex indexrow BSON document

column BSON fieldjoin embedding and linking

primary key _id fieldgroup by aggregation

source: mongodb.org

http://www.mongodb.org/display/DOCS/BSON

Embedding vs Linking

“Embedding is the nesting of objects and arrays inside a BSON document”

“Links are references between documents”

source: http://www.mongodb.org/display/DOCS/Schema+Design

MongoDB on MacOS X

$ wget http://downloads.mongodb.org/osx/mongodb-osx-x86_64-2.0.6.tgz

$ tar -zxvf mongodb-osx-x86_64-2.0.6.tgz

$ sudo mkdir -p /data/db

$ sudo chown `id -u` /data/db

Starting MongoDB

$ mongod

Mongo shell

$ mongo

Mongo shell demo

Mongo shell

> use mydb

> obama = { name: “Obama” };

> db.presidents.save(obama);

> db.presidents.ensureIndex({ name: 1 });

> db.presidents.find({name: “Obama”});

> exit

Client libraries for the JVM

• mongo-java-driver

• Morphia• Casbah

• Hammersmith

• Rogue

MongoDB Java driver

https://github.com/mongodb/mongo-java-driver/

mongo-java-driver and Maven

<dependency> <groupId>org.mongodb<groupId> <artifactId>mongo-java-driver<artifactId> <version>2.8.0<version> <dependency>

mongo-java-driver example code

Morphia

http://code.google.com/p/morphia/

Morphia example code

Casbah

https://github.com/mongodb/casbah/

Casbah

• Scala toolkit for MongoDB

• built on top of the mongo-java-driver

Casbah

• Scala idioms

• Scala collections

• fluid query syntax

https://twitter.com/mongodb/status/217291079920254976

Casbah and Maven

<dependency> <groupId>org.mongodb<groupId> <artifactId>casbah_2.9.2<artifactId> <version>2.3.0<version> <dependency>

Casbah and SBT

"org.mongodb" %% "casbah" % "2.3.0"

Casbah DBObjectimport org.mongodb.casbah.Imports._

val mongoConn = MongoConnection(hostname, port)val mongoDB = mongoConn(“test_db”)val collection = mongoDB(“test_data”)

val newObj = MongoDBObject(“a” -> “apple”, “b” -> “banana”)newObj += “c” -> “chocolate”

val a = newObject.getAs[String](“a”)// a is an Option[String]

http://api.mongodb.org/scala/casbah/current/tutorial.html

Casbah MongoDBList// MongoDBList is a Mongo-friendly Scala List

import org.mongodb.casbah.Imports._

val builder = MongoDBList.newBuilder builder += "foo" builder += "bar" builder += "x" builder += "y" val newLst = builder.result /* newLst: com.mongodb.BasicDBList = [ "foo" , "bar" , "x" , "y"] */

http://api.mongodb.org/scala/casbah/current/tutorial.html

Querying with Casbahval mongoColl = MongoConnection()("test_db")("users")val user1 = MongoDBObject("user" -> "barack", "email" -> "barack@whitehouse.gov")val user2 = MongoDBObject("user" -> "someOtherUser")mongoColl += user1mongoColl += user2mongoColl.find()// com.mongodb.casbah.MongoCursor =// MongoCursor{Iterator[DBObject] with 2 objects.}

for { x <- mongoColl} yield x/* Iterable[com.mongodb.DBObject] = List( { "_id" : { "$oid" : "4c3e2bec521142c87cc10faa"} , "user" : "obama" , "email" : "barack@whitehouse.gov"}, { "_id" : { "$oid" : "4c3e2bec521142c87dc10fbb"} , "user" : "someOtherUser"} ) */

http://api.mongodb.org/scala/casbah/current/tutorial.html

Fluid querying with Casbah DSL

val q = "email" $exists true// q: (String, com.mongodb.DBObject) =// (email,{ "$exists" : true})val users = for (x <- mongoColl.find(q)) yield xassert(users.size == 1)

http://api.mongodb.org/scala/casbah/current/tutorial.html

Hammersmith

https://github.com/bwmcadams/hammersmith

Hammersmith

• new MongoDB driver for Scala

• pure Scala

• Asynchronous

• Not production ready at this time

MongoDB at Gilt

• feature configuration service

• global navigation service

• user service

Foursquare’s Fongo project

“Fongo is an in-memory java implementation of mongo.”

“[...] primary use is for lightweight unit testing where you don't want to spin up a mongo process”

https://github.com/foursquare/fongo

Additional resources

• http://www.10gen.com/presentations

• http://www.mongodb.org

• http://www.slideshare.net/sullis

Questions?

THE END