Get Started with the Scala Driver

Install dependencies

Before you being developing, ensure you have the following dependencies installed in your development environment:

• JDK version 8 or later

• sbt version 1 or later

Create a project directory

Run the following command in your shell to create a directory called scala-quickstart for this project:

mkdir scala-quickstart

Select the tab corresponding to your operating system and run the following commands to create a build.sbt file in the scala-quickstart directory:

cd scala-quickstart
touch build.sbt

cd scala-quickstart
type nul > build.sbt

Configure your project to use the Scala driver

Navigate to your build.sbt file and add the following code to use the Scala driver in your application:

ThisBuild / scalaVersion := "2.13.16"
libraryDependencies += "org.mongodb.scala" %% "mongo-scala-driver" % "5.4.0"

This code configures your application to use Scala version 2.13.16 and Scala driver version 5.4.0.

Create a free MongoDB deployment on Atlas

Complete the Get Started with Atlas guide to set up a new Atlas account and load sample data into a new free tier MongoDB deployment.

Save your credentials

After you create your database user, save that user's username and password to a safe location for use in an upcoming step.

Find your MongoDB Atlas Connection String

To retrieve your connection string for the deployment that you created in the previous step, log in to your Atlas account and navigate to the Database section and click the Connect button for your new deployment.

Then, select the Drivers option under the Connect to your application header. Select "Scala" from the Driver selection menu and the version that best matches the version you installed from the Version selection menu.

Copy your Connection String

Click the button on the right of the connection string to copy it to your clipboard, as shown in the following screenshot:

Update the Placeholders

Paste this connection string into a file in your preferred text editor and replace the <db_username> and <db_password> placeholders with your database user's username and password.

Save this file to a safe location for use in the next step.

Create an application file

Navigate to the scala-quickstart directory that you made in the Download and Install step of this guide and create the src/main/scala/quickstart nested directories.

Select the tab corresponding to your operating system and run the following commands to create a Main.scala file in the quickstart subdirectory:

cd src/main/scala/quickstart
touch Main.scala

cd src/main/scala/quickstart
type nul > Main.scala

Add helper methods

Add the following Helpers.scala file from the driver source code to the src/main/scala/quickstart directory:

package quickstart
import java.util.concurrent.TimeUnit
import scala.concurrent.Await
import scala.concurrent.duration.Duration
import org.mongodb.scala._
object Helpers {
  implicit class DocumentObservable[C](val observable: Observable[Document]) extends ImplicitObservable[Document] {
    override val converter: (Document) => String = (doc) => doc.toJson
  }
  implicit class GenericObservable[C](val observable: Observable[C]) extends ImplicitObservable[C] {
    override val converter: (C) => String = (doc) => Option(doc).map(_.toString).getOrElse("")
  }
  trait ImplicitObservable[C] {
    val observable: Observable[C]
    val converter: (C) => String
    def results(): Seq[C] = Await.result(observable.toFuture(), Duration(10, TimeUnit.SECONDS))
    def headResult() = Await.result(observable.head(), Duration(10, TimeUnit.SECONDS))
    def printResults(initial: String = ""): Unit = {
      if (initial.length > 0) print(initial)
      results().foreach(res => println(converter(res)))
    }
    def printHeadResult(initial: String = ""): Unit = println(s"${initial}${converter(headResult())}")
  }
}

This file allows you to access helper methods for printing query results.

Add your application code

Copy and paste the following code into the Main.scala file, which queries the movies collection in the sample_mflix database:

package quickstart
import org.mongodb.scala._
import org.mongodb.scala.model.Filters._
import Helpers._
object Main {
  def main(args: Array[String]): Unit = {
    val mongoClient = MongoClient("<connection string>")
    val database: MongoDatabase = 
       mongoClient.getDatabase("sample_mflix")
    val collection: MongoCollection[Document] = 
       database.getCollection("movies")
    val filter = equal("title", "The Shawshank Redemption")
    collection.find(filter).printResults()
    mongoClient.close()
    
  }
}

Assign the connection string

Replace the <connection string> placeholder with the connection string that you copied from the Create a Connection String step of this guide.

Run your Scala application

In your project root directory, run the following commands to start the sbt shell and run your application:

sbt
run

The command line output contains details about the retrieved movie document:

{"_id": {"$oid": "..."}, ... , "genres": ["Crime", "Drama"], "rated": "R",
"metacritic": 80, "title": "The Shawshank Redemption", ... }

If you encounter an error or see no output, ensure that you specified the proper connection string in the Main.scala file and that you loaded the sample data.

exit