MongoDB Scala Driver doesn't allow use Map collection in case class - mongodb

Question

I just started using MongoDB and I'm trying to write a small application to test Mongo with Scala. I created the following case class in order to cast the Documents to a Scala class:
case class User(
_id: ObjectId,
userId: String,
items: Map[String, Int]
)
object User {
def apply(userId: String , items: Map[String, Int]): User =
new User(new ObjectId, userId, items)
implicit val codecRegistry: CodecRegistry =
fromRegistries(fromProviders(classOf[User]), DEFAULT_CODEC_REGISTRY)
}
I get the following error but I don't know why since the Map keys are in fact strings.
[ERROR] error: Maps must contain string types for keys
[INFO] implicit val codecRegistry: CodecRegistry = fromRegistries (fromProviders (classOf [User]), DEFAULT_CODEC_REGISTRY)
[INFO] ^
[ERROR] one error found
I'm also applying the codecRegistry to the MongoDatabase.
Thank you very much.

Answer 1

The problem was that I was using a version of the driver that is compiled for Scala 2.11 and not 2.12. By changing the Maven dependency from
<dependency>
<groupId>org.mongodb.scala</groupId>
<artifactId>mongo-scala-driver_2.11</artifactId>
<version>2.2.1</version>
</dependency>
to
<dependency>
<groupId>org.mongodb.scala</groupId>
<artifactId>mongo-scala-driver_2.12</artifactId>
<version>2.2.1</version>
</dependency>
solved the problem.