add a document in mongodb using Play/reactivemongoplugin - scala

Question

I am writing an Action in Play which should add a Document in MongoDB if it doesn't exist already. I have tried two approaches but none of them are working. I am stuck around how to handle Future returned by reactivemongoplugin
The Action gets JSON data. It valides it. If JSON is OK, I check if the user exists (look at firstname). If it doesnt, I want to add it else return an error. I am unable to combine ReactiveMongoPlugin's 'find' and 'insert' methods in the same action
Approach 1** - This doesn't compile because the code returns scala.concurrent.Future[play.api.mvc.SimpleResult] while it requires play.api.mvc.SimpleResult. I know that it is because I am using a map inside a map.
def registrationRequest = Action.async(parse.json) { request => {
Logger.debug("received message:" + request)
Logger.debug("received message:" + request.body)
val jr: JsResult[User2] = request.body.validate[User2]
Logger.debug("jr is " + jr)
jr match {
case s: JsSuccess[User2] => {
val user = s.get
Logger.debug("opening database connection")
val driver = new MongoDriver()
val connection = driver.connection(List("localhost"))
val db = connection.db("website-db")
val collection = db.collection[BSONCollection]("users")
val query = BSONDocument("user.firstname" -> user.firstName)
Logger.debug("query is:" + query)
//result is of type Future[Option[BSONDocument]]
val findFuture:Future[Option[BSONDocument]] = collection.find(query).one
findFuture.map(option => option match {
case None => {
//no record. Can add
Logger.debug("No record from mongo: Can add")
val newUserDoc = BSONDocument (
"id" -> user.id,
"user" -> BSONDocument (
"firstname" -> user.firstName,
"lastname" -> user.lastName,
"email" -> BSONArray (user.email (0) ),
"password" -> user.password,
"address" -> BSONDocument (
"street" -> user.address.street,
"country" -> user.address.country
)
)
)
//addResult is of type Future[LastError]
//this code is problamatic. I am calling a map within a map which creates a Future[Future[Result]]. I need only Future[Result]
val insertResult = collection.insert (newUserDoc)
insertResult.map(le=>{
if(le.ok) {
Logger.debug("insertFuture map")
val ack = Acknowledgment(0, "insert success: ")
Logger.debug("insert success:" + Json.toJson(ack))
Ok(Json.toJson(ack))
}else {
Logger.debug("not inserting")
val ack = Acknowledgment (0, "duplicate: ")
Logger.debug ("fail ack:" + Json.toJson (ack) )
BadRequest (Json.toJson (ack) )
}
})}
case Some(x) => {
//duplicae record
Logger.debug("error from Mongo. Duplicate:" + x)
val ack = Acknowledgment(0, "duplicate: " + x.toString())
Logger.debug("fail ack:" + Json.toJson(ack))
BadRequest(Json.toJson(ack))
}
})
//findFutureResult is a Future[Int]
case f: JsError => Future.successful({
Logger.debug("error: " + JsError.toFlatJson(f))
val ack = Acknowledgment(0, JsError.toFlatJson(f).toString())
Logger.debug("fail ack:" + Json.toJson(ack))
BadRequest(Json.toJson(ack))
})
}
}
}
Approach 2 - In this approach, I broke the steps to avoid calling map within map. Following code is for JsSuccess part
case s: JsSuccess[User2] => {
val user = s.get
Logger.debug("opening database connection")
val driver = new MongoDriver()
val connection = driver.connection(List("localhost"))
val db = connection.db("website-db")
val collection = db.collection[BSONCollection]("users")
val query = BSONDocument("user.firstname" -> user.firstName)
Logger.debug("query is:" + query)
//result is of type Future[Option[BSONDocument]]
val findFuture:Future[Option[BSONDocument]] = collection.find(query).one
//findFutureResult is a Future[Int]
//to avoid calling map within map, I am creating single Futures which would convey result of one Future to another.
val findFutureResult:Future[Int] = findFuture.map(option => option match {
case None => {
//no record. Can add
Logger.debug("No record from mongo: Can add")
1 //return of 1 means record can be added
}
case Some(x) => {
//duplicae record
Logger.debug("error from Mongo. Duplicate:" + x)
2 //return of 2 means record cannot be added.
}
})
//this code would return LastError. the value of LastError can be used to check if insert was performed or not. Accordingly, I want to send OK or BadRequest
val insertFuture:Future[Future[LastError]] = findFutureResult.map(r => {r match {
case 1 => {
Logger.debug("findFutureResult map. Adding doc")
val newUserDoc = BSONDocument (
"id" -> user.id,
"user" -> BSONDocument (
"firstname" -> user.firstName,
"lastname" -> user.lastName,
"email" -> BSONArray (user.email (0) ),
"password" -> user.password,
"address" -> BSONDocument (
"street" -> user.address.street,
"country" -> user.address.country
)
)
)
//addResult is of type Future[LastError]
collection.insert (newUserDoc)
}
case 2 => Future.successful({
Logger.debug("findFutureResultmap. Not adding a duplicate")
LastError(false,None, None, None, None, 0,false )
})
}
})
//this is the problematic code. How do i check value of LastError? insertFuture is Future[Future[LastError]] and not Future[LastError]
insertFuture.map(lef=>{ lef.map(le=>{ // I cannot call map inside map as explained in approach 1
if(le.ok) {
Logger.debug("insertFuture map")
val ack = Acknowledgment(0, "insert success: ")
Logger.debug("insert success:" + Json.toJson(ack))
Ok(Json.toJson(ack))
}
else {
Logger.debug("not inserting")
val ack = Acknowledgment (0, "duplicate: ")
Logger.debug ("fail ack:" + Json.toJson (ack) )
BadRequest (Json.toJson (ack) )
}
})})
}
}
I know what the problem is in the code. I do not know how to solve it. I assume my approach is not bad - I want to check database before inserting in it but I am unable to fit it around reactivemongo apis and Futures

Answer 1

flatMap worked. Thank you Cyrille Corpet and cchantep
def registrationRequest = Action.async(parse.json) { request => {
Logger.debug("received message:" + request)
Logger.debug("received message:" + request.body)
val jr: JsResult[User2] = request.body.validate[User2]
Logger.debug("jr is " + jr)
jr match {
case s: JsSuccess[User2] => {
val user = s.get
Logger.debug("opening database connection")
val driver = new MongoDriver()
val connection = driver.connection(List("localhost"))
val db = connection.db("website-db")
val collection = db.collection[BSONCollection]("users")
val query = BSONDocument("user.firstname" -> user.firstName)
Logger.debug("query is:" + query)
//result is of type Future[Option[BSONDocument]]
val findFuture: Future[Option[BSONDocument]] = collection.find(query).one
val insertFuture: Future[Future[LastError]] = findFuture.map(option => option match {
case None => {
//no record. Can add
Logger.debug("No record from mongo: Can add")
//1
Logger.debug("findFutureResult map. Adding doc")
val newUserDoc = BSONDocument(
"id" -> user.id,
"user" -> BSONDocument(
"firstname" -> user.firstName,
"lastname" -> user.lastName,
"email" -> BSONArray(user.email(0)),
"password" -> user.password,
"address" -> BSONDocument(
"street" -> user.address.street,
"country" -> user.address.country
)
)
)
//addResult is of type Future[LastError]
collection.insert(newUserDoc)
}
case Some(x) => {
//duplicae record
Logger.debug("error from Mongo. Duplicate:" + x)
//2
Future.successful({
Logger.debug("findFutureResultmap. Not adding a duplicate")
LastError(false, None, None, None, None, 0, false)
})
}
})
insertFuture.flatMap(lef => {
lef.map(le => {
if (le.ok) {
Logger.debug("insertFuture map")
val ack = Acknowledgment(0, "insert success: ")
Logger.debug("insert success:" + Json.toJson(ack))
Ok(Json.toJson(ack))
}
else {
Logger.debug("not inserting")
val ack = Acknowledgment(0, "duplicate: ")
Logger.debug("fail ack:" + Json.toJson(ack))
BadRequest(Json.toJson(ack))
}
})
//findFutureResult is a Future[Int]
})
}
case f: JsError => Future.successful({
Logger.debug("error: " + JsError.toFlatJson(f))
val ack = Acknowledgment(0, JsError.toFlatJson(f).toString())
Logger.debug("fail ack:" + Json.toJson(ack))
BadRequest(Json.toJson(ack))
})
}
}
}