outr / giant-scala   1.5.1


Advanced functionality for working with MongoDB in Scala

Scala versions: 2.13 2.12 2.11
Scala.js versions: 1.x 0.6
sbt plugins: 1.0


CI Gitter Maven Central Scala version support javadoc

GiantScala is wrapper on top of the Scala MongoDB driver to provide higher level functionality and better type-safety.

Quick Start

For people that want to skip the explanations and see it action, this is the place to start!

Dependency Configuration

libraryDependencies += "com.outr" %% "giant-scala" % "1.5.0"

If you are developing a cross-project with Scala.js support:

libraryDependencies += "com.outr" %%% "giant-scala" % "1.5.0"

Note: while MongoDB obviously doesn't work in the browser, the purpose of the Scala.js functionality is to allow shared model objects that extend from the base ModelObject.

Case Classes

Most of the functionality in GiantScala is accessible via the import:

import com.outr.giantscala._

In order to represent our object, we begin with a case class:

case class Person(_id: String,
                  name: String,
                  age: Int,
                  created: Long = System.currentTimeMillis(),
                  modified: Long = System.currentTimeMillis()) extends ModelObject

Notice that this case class extends from ModelObject. This is a simple trait that defines three required fields for all model objects:

  • _id: String: A unique identifier in the database
  • created: Long: The creation date of this document
  • modified: Long: The last modified date of this document


In order to represent the tie-in to an actual MongoDB instance, we must create a database object:

object Database extends MongoDatabase(name = "giant-scala-tutorial") {
    ... collections listed here ...


Now that we have a Person case class, we need to tie it to a database collection. To do this, we use the DBCollection object:

class PersonCollection extends DBCollection[Person]("person", Database) {
  override val converter: Converter[Person] = Converter.auto[Person]

  val name: Field[String] = Field("name")
  val age: Field[Int] = Field("age")
  val created: Field[Long] = Field("created")
  val modified: Field[Long] = Field("modified")
  val _id: Field[String] = Field("_id")

  override def indexes: List[Index] = List(

There's a lot of boilerplate code in this class, but we can simplify this setup if we use the GiantScala SBT plugin. Add the following line to your project/plugins.sbt file in your project:

addSbtPlugin("com.outr" % "giant-scala-plugin" % "1.2.0")

Now you can run sbt generateDBModels and a PersonModel class will be generated in your source directory. This simplifies set up by changing the signature of the PersonCollection to:

class PersonCollection extends PersonModel("person", Database) {
  override def indexes: List[Index] = List(

The fields and converter are all defined in the PersonModel class. The only things left to define are indexes.

Now, we need to update our Database to include the collection:

object Database extends MongoDatabase(name = "giant-scala-tutorial") {
    val person: PersonCollection = new PersonCollection

Initialize the Database

GiantScala supports advanced features like database upgrades that are handled during the initialization phase:


Note that init() returns a IO[Unit] that must complete before the database is fully usable. We'll talk about database upgrades later in this tutorial.

Inserting a Person

Now that our database is fully defined we can easily insert a person:

Database.person.insert(Person(_id = "john.doe", name = "John Doe", age = 30))

Note that this returns a IO[Either[DBFailure, Person]] representing the success or failure of the operation.

Querying a Person

Now that there's a person in our database, we can query them back with:


This will return a IO[List[Person]]

For a more advanced query, GiantScala offers a type-safe implementation of aggregation:

import Database.person._

  .`match`(name === "John Doe")

Note that this will return a IO[List[Person]].

If we wanted a more simplistic, limited type to result from aggregation we could do:

import Database.person._

case class SimplePerson(_id: String, name: String)

  .`match`(name === "John Doe")

This will return a IO[List[SimplePerson]]. This can be extremely useful for complex queries to avoid being bound to the original type. It is also worth noting that instead of calling toList you can call toQuery() and it will generate a String representation of the query that can be directly pasted into the mongo REPL. This allows for much easier testing of complex queries.

Advanced Features (TODO: Give examples for each of these)

  • Database Upgrades: Extend from DatabaseUpgrade and call Database.register(upgrade) before calling Database.init()
  • Batch Operations: GiantScala provides several features for batch operations. The typical path is to simply call collection.batch to get started
  • Key/Value Store: Database.store provides lots of functionality for storing key/value data into the database
  • Realtime Monitoring: GiantScala provides advanced functionality to monitor changes happening in real-time to the database (see collection.monitor)