Casbah

CasbahPlay.scala

import com.mongodb.casbah.Imports._

class CasbahPlay {
  private val mongoConn = MongoConnection()
  private val coll = mongoConn("mongotalk")("unicorns")

  def getWeight(name: String) = {
    val unicorn = (coll.findOne(MongoDBObject("name" -> name)).get

    // This is returning Option[Int] = Some(450.0)
    // Which causes a ClassCastException
    unicorn.getAs[Int]("weight")
  }
}

class MyMain extends App {
  val casbahPlay = new CasbahPlay
  val weight = casbahPlay.getWeight("Aurora") // Exception!
}

unicorns.json

db.unicorns.insert({name: 'Aurora', dob: new Date(1991, 0, 24, 13, 0), loves:['carrot', 'grape'], weight: 450, gender: 'f', vampires: 43});

You created the data from the shell. Javascript lacks an integer type - everything is a float.

SOOOOO... By default all your numbers are saved as BSON Double types. Javascript automatically shows Floats w/ no decimal as if they're an int. But the BSON stores them as a double.

scala> m("test")("unicorns")
res0: com.mongodb.casbah.MongoCollection = MongoCollection({ "_id" : { "$oid" : "4ed6c0d774c898556fc56e3e"} , "name" : "Aurora" , "dob" : { "$date" : "1991-01-24T13:00:00Z"} , "loves" : [ "carrot" , "grape"] , "weight" : 450.0 , "gender" : "f" , "vampires" : 43.0})

MongoDB's shell comes with a few built-in type constructors including NumberInt which can be used to explicitly create a BSON Integer:

  db.unicorns.insert({name: 'Aurora', dob: new Date(1991, 0, 24, 13, 0), loves:['carrot', 'grape'], weight: NumberInt(450), gender: 'f', vampires: NumberInt(43)});

Renders now as:

 scala> m("test")("unicorns")
 res0: com.mongodb.casbah.MongoCollection = MongoCollection({ "_id" : { "$oid" : "4ed6c1c4f201dff59ce8245c"} , "name" : "Aurora" , "dob" : { "$date" : "1991-01-24T13:00:00Z"} , "loves" : [ "carrot" , "grape"] , "weight" : 450 , "gender" : "f" , "vampires" : 43})