import com.mongodb.casbah.Imports._
/*
* Simple test of the MongoDB Aggregation Framework via Casbah
*
* [Note: only works on MongoDB 2.1+]
*
* The "students" collection consists of student test score records that [simplified] look like this:
*
{
"_id" : ObjectId("4f436e581a8819c9391c9e77"),
"id" : "1000000321",
"lname" : "Simpson",
"fname" : "Bobby",
"scores" : [
{
"score" : 14,
"dname" : "ACADEMICS PLUS SCHOOL DISTRICT",
"sname" : "Test School 6040702",
"tyear" : "2007",
"tname" : "Lit_Scale",
"grade" : "3"
},
{
"score" : 557,
"dname" : "ACADEMICS PLUS SCHOOL DISTRICT",
"sname" : "Test School 6040702",
"tyear" : "2007",
"tname" : "Lit_Perf",
"grade" : "3"
},
{
"score" : 15,
"dname" : "ACADEMICS PLUS SCHOOL DISTRICT",
"sname" : "Test School 6040702",
"tyear" : "2008",
"tname" : "Lit_Scale",
"grade" : "4"
}
]
}
*
* This example unwinds the scores and groups them
* to determine the unique values of the tests, years and grades fields.
*
*/
object AggregationFrameworkTest extends App {
val mongoConn = MongoConnection()
val db = mongoConn("hivedbmig")
def aggregationResult(collectionName:String, pipeline: MongoDBList) = {
db.command(MongoDBObject("aggregate" -> collectionName, "pipeline" -> pipeline)).get("result")
}
val pipebuilder = MongoDBList.newBuilder
pipebuilder += MongoDBObject("$unwind" -> "$scores")
pipebuilder += MongoDBObject("$group" -> MongoDBObject(
"_id" -> "all", // constant, so we'll just create one bucket
"tests" -> MongoDBObject("$addToSet" -> "$scores.tname"),
"years" -> MongoDBObject("$addToSet" -> "$scores.tyear"),
"grades" -> MongoDBObject("$addToSet" -> "$scores.grade")))
val pipeline = pipebuilder.result()
aggregationResult("students", pipeline) match {
case list: BasicDBList => list.foreach(println(_))
case _ => println("didn't work")
}
// { "_id" : "all" , "tests" : [ "ACT_Comp" , "FPQ4_Score" , "Lit_Growth" , "Math_Scale" , "Bio_Scale" , "Geo_Scale" , "Geo_Growth" , "Math_Growth" , "Alg_Scale" , "ACT_Math" , "ACT_Eng" , "Alg_Growth" , "Sci_Scale" , "Lit_Scale"] , "years" : [ "2011" , "2006" , "2008" , "2009" , "2007" , "2010"] , "grades" : [ "5" , "4" , "7" , "11" , "6" , "3" , "8"]}
}