CODEWITHSUNDEEP
scalafuture
j3d
j3d

Reputation: 9724

Scala: Future, zip, and recover

The following code compiles and works as expected...

def find1(selector: JsValue): Future[Seq[String]]
def find2(selector: JsValue): Future[Seq[String]]

find1(Json.obj("name" -> "Joe")) zip
find2(Json.obj("name" -> "Tim")) map { case (result1, result2) =>
  val result = result1 ++ result2
  ...
}

... but if I add recover to handle possible errors like this...

find1(Json.obj("name" -> "Joe")) zip
find2(Json.obj("name" -> "Tim")) map { case (result1, result2) =>
  val result = result1 ++ result2
  ...
}.recover { case e =>
  ...
}

... I always get the following error:

[error] /home/j3d/test/TestController.scala:558: missing parameter type for expanded function
[error] The argument types of an anonymous function must be fully known. (SLS 8.5)
[error] Expected type was: ?
[error]        find2(Json.obj("name" -> "Tim")) map { case (result1, result2) =>
[error]                                             ^
[error] one error found

I've tried to specify the types of result1 and result2 like this...

find1(Json.obj("name" -> "Joe")) zip
find2(Json.obj("name" -> "Tim")) map { case (result1: Seq[String], result2: Seq[String]) =>
  val result = result1 ++ result2
  ...
}.recover { case e =>
  ...
}

... but nothing changes, i.e. it only compiles without recover. Am I missing something?

Upvotes: 0

Views: 798

Answers (1)

Shyamendra Solanki
Shyamendra Solanki

Reputation: 8851

use the operator notation throughout.

find1(Json.obj("name" -> "Joe")) zip
find2(Json.obj("name" -> "Tim")) map { case (result1, result2) =>
   val result = result1 ++ result2
   ...
} recover { case e => // removed the '.' 
  ...
}

Upvotes: 2

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