My talk about ReactiveMongo driver at Moscow Scala user group May meetup

1. Reactive Mongo
Asynchronous driver for MongoDB

2. About me
• My name is Andrey Neverov
• “General rhetoric”
• scala since 2011
• now: scala, akka, spray, mongodb
• contribute to reactive mongo

3. Plan
1. What is reactive mongo
2. Connecting
3. Queries
4. Working with data
5. Streaming
6. Reactive Mongo + Play

4. Reactive Mongo
• Asynchronous driver
• Non-blocking I/O
• Scalability
• Streaming
• GridFS

5. val driver = new MongoDriver
val connection = driver.
connection(List(“localhost"))
val db = connection.db("db_name")
val collection =
db.collection(“coll_name")
Connecting

6. Queries
val query = BSONDocument(
“age” -> BSONDocument(
“$gt” -> 5
)
)

7. Queries
val animalsOlderThanFive =
collection.
find(query).
cursor[BSONDocument].
collect[List]()
!
// Future[List[BSONDocument]]

8. Queries
animalsOlderThanFive.map {
case animals: List[Animal] => …
} recover {
case t: Throwable => // fail!
}

9. Readers
case class Animal(_id: BSONObjectID,
age: Int)
object Animal {
implicit val reader =
new BSONDocumentReader[Animal] {
def read(doc: BSONDocument) = {
Animal(…)
}}}

10. Readers
object Animal {
import reactivemongo.bson.Macros
!
val handler = Macros.handler[Animal]
}

11. Readers
val animalsFuture =
collection.
find(query).
cursor[Animal].
collect[List]()
!

12. Streaming
// Enumerator[BSONDocument]
val enumeratorOfAnimals =
collection.
find(query).
cursor[BSONDocument].
enumerate()

13. Streaming
// Iteratee[BSONDocument, Unit]
val process: = Iteratee.foreach { a =>
val name = a[String]("name")
val pretty = BSONDocument.pretty(a)
println(s"got $name of: $pretty")
}

14. Streaming
enumeratorOfAnimals.apply(process)
!
or:
!
enumeratorOfAnimals |>>> process

15. Play
• Play json <-> Reactive mongo bson
• Async actions
• Iteratees
• GridFS

16. Play
object Application extends Controller
with MongoController {
!
def collection: JSONCollection =
db.collection(“animals")
}

17. Play
object JsonFormats {
import play.api.libs.json.Json
import play.api.data._
import play.api.data.Forms._
!
implicit val format =
Json.format[Animal]
}

18. Play
def findByName(name: String) =
Action.async {
collection.
find(Json.obj("name" -> name))
cursor[JsObject].
collect[List]() map {
case animals =>
Ok(Json.arr(animals))
}}

19. Play
def fromJson =
Action.async(parse.json) { r =>
r.body.validate[Animal].map { a =>
collection.insert(a).map { … }
}.getOrElse {
Future(BadRequest(“bad json"))
}}

20. Play
def upload =
Action(gridFSBodyParser(gfs)) { r =>
// Future[ReadFile[BSONValue]]
val futureFile = r.body.files.head.ref
futureFile.map { file =>
// do something
Ok
}
}

21. Thanks!
• http://www.mongodb.org/
• http://reactivemongo.org/
• https://github.com/ReactiveMongo/ReactiveMongo/
• https://github.com/neverov