CODEWITHSUNDEEP
scalaplayframeworkfuture
Damacharla Ashok Kumar
Damacharla Ashok Kumar

Reputation: 51

Play Scala - Found Future[String] but expected String error

I am new to Play Scala. Below code snippet I am trying to use to expose an API. Its failing with the below error.

type mismatch;
 found   : scala.concurrent.Future[String]
 required: String

API source:

def getStrategy(date: String) = Action.async {
    val currentDate:String = toString(DateTime.now.minusDays(1))
    getDecision(date, currentDate).map(lastError => Ok("No Strategy found:%s".format(lastError)))
  }

  def getDecision(reqestedDate:String, currentDate:String): Future[String] = {
    getForecastPrice(reqestedDate).map(forecastPrice =>
      getCurrentPrice(currentDate).map(currentPrice => 
        getCall(currentPrice, forecastPrice)
      )
    )
  }

  def getForecastPrice(requestedDate:String): Future[Option[Double]] = {
    predictionRepo.getPrediction(requestedDate).map( maybePrediction =>
      maybePrediction.map ( fPrice => fPrice.price )
    )
  }

  def getCurrentPrice(currentDate:String): Future[Option[Double]] = {
    priceRepo.getPrice(currentDate).map ( maybePrice =>
      maybePrice.map ( cPrice => cPrice.price )
    )
  }

  def getCall(currentPrice:Option[Double], forcastPrice:Option[Double]): String = {
    var decision = ""
    println("currentPrice:" + currentPrice)
    println("forcastPrice:" + forcastPrice)

    if(currentPrice.isDefined && forcastPrice.isDefined) {
      var currentPriceValue = currentPrice.get.toDouble
      var forcastPriceValue = forcastPrice.get.toDouble

      if((currentPriceValue*5/100) < (currentPriceValue - forcastPriceValue)) {
        decision = "BUY"
      } else if((currentPriceValue*5/100) > (currentPriceValue - forcastPriceValue)) {
        decision = "SELL"
      } else {
        decision = "HOLD"
      }
    }
    return decision
  }

Error in the above code is shwon at the below location.

getCurrentPrice(currentDate).map(currentPrice =>

Could you please help me to find the reason for this issue?

Upvotes: 0

Views: 463

Answers (2)

talkdatatome
talkdatatome

Reputation: 664

You can use for comprehension rather than using a map inside another map. The sample code would be something like this.

for(
getForecastPriceResult <- getForecastPrice(requestedDate);
getCurrentPriceResult <- getCurrentPrice(currentDate)
) yield(getCall(getForecastPriceResult,getCurrentPriceResult))

Upvotes: 2

Harald Gliebe
Harald Gliebe

Reputation: 7544

Can you change the first map in getDecision to flatMap:

def getDecision(reqestedDate:String, currentDate:String): Future[String] = {
    getForecastPrice(reqestedDate).flatMap(forecastPrice =>
      getCurrentPrice(currentDate).map(currentPrice => 
        getCall(currentPrice, forecastPrice)
      )
    )
  }

With the current code the result type would Future[Future[String]]

Upvotes: 2

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