ReactiveMongo Extensions

The goal of ReactiveMongo Extensions is to provide all the necessary tools for ReactiveMongo other than the core functionality.

Since ReactiveMongo 0.11, some useful functions are available directly in the driver, so these extensions are not updated, and it's recommended to directly use the driver. Some third party projects like ReactiveMongo-Criteria can also be used.

Introduction

ReactiveMongo Extensions comes as 2 separate packages which are reactivemongo-extensions-bson and reactivemongo-extensions-json. reactivemongo-extensions-bson package targets ReactiveMongo, while reactivemongo-extensions-json targets Play-ReactiveMongo.

DAOs to Serve You

DAOs provide an abstraction layer on top of ReactiveMongo adding higher level APIs like findOne, findById, count, foreach, fold, etc. ReactiveMongo Extensions currently provides two DAO types for collections of documents: reactivemongo.extensions.dao.BsonDao for BSONCollection and reactivemongo.extensions.dao.JsonDao for JSONCollection. There are also two other DAO types operating on GridFS: reactivemongo.extensions.dao.BsonFileDao and reactivemongo.extensions.dao.JsonFileDao.

You will need to define a DAO for each of your models(case classes).

Below is a sample model.

import reactivemongo.bson._
import reactivemongo.extensions.dao.Handlers._

case class Person(
  _id: BSONObjectID = BSONObjectID.generate,
  name: String,
  surname: String,
  age: Int)

object Person {
  implicit val personHandler = Macros.handler[Person]
}

To define a BsonDao for the Person model you just need to extend BsonDao.

import reactivemongo.api.{ MongoDriver, DB }
import reactivemongo.bson.BSONObjectID
import reactivemongo.bson.DefaultBSONHandlers._
import reactivemongo.extensions.dao.BsonDao
import scala.concurrent.ExecutionContext.Implicits.global

object MongoContext {
  val driver = new MongoDriver
  val connection = driver.connection(List("localhost"))
  def db: DB = connection("reactivemongo-extensions")
}

object PersonDao extends BsonDao[Person, BSONObjectID](MongoContext.db, "persons")

From now on you can insert a Person instance, find it by id, find a random person or etc.

val person1 = Person(name = "foo", surname = "bar", age = 16)
val person2 = Person(name = "fehmi can", surname = "saglam", age = 32)
val person3 = Person(name = "ali", surname = "veli", age = 64)

PersonDao.insert(person1)
PersonDao.insert(Seq(person2, person3))

PersonDao.findById(person1._id)
PersonDao.findRandom(BSONDocument("age" -> BSONDocument("$ne" -> 16)))

Read more about BsonDao here and JsonDao here.

Query DSL for Easy Query Construction

There are also DSL helpers for each DAO type, which are reactivemongo.extensions.dsl.BsonDsl and reactivemongo.extensions.json.dsl.JsonDsl. DSL helpers provide utilities to easily construct JSON or BSON queries.

By mixing in or importing BsonDsl you could write the query above like this:

import reactivemongo.extensions.dsl.BsonDsl._

PersonDao.findRandom("age" $gt 16 $lt 32)

Read more about Query DSL here.

Criteria DSL

An alternative providing such DSL extension can be found as a third party project.

The Criteria DSL provides the ablity to formulate queries thusly:

  // Using an Untyped.criteria
  {
  import Untyped._

  // The MongoDB properties referenced are not enforced by the compiler
  // to belong to any particular type.  This is what is meant by "Untyped".
  val adhoc = criteria.firstName === "Jack" && criteria.age >= 18;
  val cursor = collection.find(adhoc).cursor[BSONDocument];
  }

  {
  // Using a Typed criteria which restricts properties to the
  // given type.
  import Typed._

  case class ExampleDocument (aProperty : String, another : Int)

  val byKnownProperties = criteria[ExampleDocument].aProperty =~ "^[A-Z]\\w+" &&
    criteria[ExampleDocument].another > 0;
  val cursor = collection.find(byKnownProperties).cursor[BSONDocument];
  }

Read more about Criteria DSL here.

Model Life Cyle

By defining a life cycle object, one can preprocess all models before being persisted or perform specific actions after life cycle events. This can be useful for updating temporal fields on all model instances before persisting.

import reactivemongo.bson._
import reactivemongo.extensions.dao.LifeCycle
import reactivemongo.extensions.dao.Handlers._
import reactivemongo.extensions.util.Logger
import org.joda.time.DateTime

case class TemporalModel(
  _id: BSONObjectID = BSONObjectID.generate,
  name: String,
  surname: String,
  createdAt: DateTime = DateTime.now,
  updatedAt: DateTime = DateTime.now)

object TemporalModel {
  implicit val temporalModelFormat = Macros.handler[TemporalModel]

  implicit object TemporalModelLifeCycle extends LifeCycle[TemporalModel, BSONObjectID] {
    def prePersist(model: TemporalModel): TemporalModel = {
      Logger.debug(s"prePersist $model")
      model.copy(updatedAt = DateTime.now)
    }
    def postPersist(model: TemporalModel): Unit = {
      Logger.debug(s"postPersist $model")
    }
    def preRemove(id: BSONObjectID): Unit = {
      Logger.debug(s"preRemove $id")
    }
    def postRemove(id: BSONObjectID): Unit = {
      Logger.debug(s"postRemove $id")
    }
    def ensuredIndexes(): Unit = {
      Logger.debug("ensuredIndexes")
    }
  }
}

Auto Indexes

ReactiveMongo Extensions support auto indexes which ensures indexes on DAO load.

object PersonDao extends {
  override val autoIndexes = Seq(
    Index(Seq("name" -> IndexType.Ascending), unique = true, background = true),
    Index(Seq("age" -> IndexType.Ascending), background = true)
  )
} with BsonDao[Person, BSONObjectID](MongoContext.db, "persons")

Default Write Concern

You can override writeConcern in your DAO definition which defaults to GetLastError().

object PersonDao extends BsonDao[Person, BSONObjectID](MongoContext.db, "persons") {
  override def defaultWriteConcern = GetLastError(j = true)
}

Fixtures for easy data loading

You can define your fixtures using HOCON. Lexical scopes are supported in addition to HOCON spec.

persons.conf

_predef {
    country: TC
}

# "persons" collection
persons {
    person1 {
        _id: _id_person1
        name: Ali
        surname: Veli
        fullname: ${name} ${surname}
        age: 32
        salary: 999.85
        time: 12345678900
        country: ${_predef.country}
    }

    person2 {
        _id: _id_person2
        name: Haydar
        surname: Cabbar
        fullname: ${name} ${surname}
        age: ${person1.age}
        salary: { "$double": 1000.0 }
        time: 12345678999
        country: ${_predef.country}
    }
}

events.conf

# Predefined reusable values
_predef {
    location: {
        city: Ankara
        place: Salon
    }
}

# "events" collection
events {
    event1 {
        _id: _id_event1
        title: Developer workshop
        organizer: ${persons.person1.fullname}
        location: ${_predef.location}
    }
}

After defining your fixtures you can load them using BsonFixtures or JsonFixtures.

import reactivemongo.extensions.bson.fixtures.BsonFixtures

BsonFixtures(db).load("persons.conf", "events.conf")

~ Operator for the Happy Path

While composing futures with for comprehensions, handling option values can be cumbersome. ~ operator converts a Future[Option[T]] to Future[T]. It throws a java.util.NoSuchElementException if the Option is None. Then you can check the exception in Future.recover.

import reactivemongo.extensions.Implicits._

(for {
  model1 <- ~dao.findOne("none" $eq "unknown")
  model2 <- ~dao.findOne("none" $eq "unknown")
  result <- compute(model1, model2)
} yield result) recover {
  case ex: java.util.NoSuchElementException =>
    println("Option is None")
    throw ex
}

Using ReactiveMongo Extensions in your project

The general format is that release a.b.c.d is compatible with ReactiveMongo a.b.c. Current version matrix is below:

reactivemongo-extensions-bson	Target ReactiveMongo version
0.10.0.0-SNAPSHOT	0.10.0

reactivemongo-extensions-json	Target Play-ReactiveMongo version
0.10.0.0-SNAPSHOT	0.10.2

Note: Only available for scala 2.10.

If you use SBT, you just have to edit build.sbt and add the following:

resolvers += "Sonatype Snapshots" at "https://oss.sonatype.org/content/repositories/snapshots/"

libraryDependencies ++= Seq(
  "org.reactivemongo" %% "reactivemongo-extensions-bson" % "0.10.0.0-SNAPSHOT"
)

or

resolvers += "Sonatype Snapshots" at "https://oss.sonatype.org/content/repositories/snapshots/"

libraryDependencies ++= Seq(
  "org.reactivemongo" %% "reactivemongo-extensions-json" % "0.10.0.0-SNAPSHOT"
)