CODEWITHSUNDEEP
scalaobjectdictionary
Levijatanu
Levijatanu

Reputation: 418

Map containing Objects not working as expected Scala

Trying to understand basic Scala concepts. Why is this code not compiling ? 

 case class User(
               id: Int,
               firstName: String,
               lastName: String,
               age: Int,
               gender: Option[String])

object UserRepository {
 val users = Map
 ( 1 ->  User(1, "John", "Doe", 32, Some("male")),
   2 -> User(2, "Johanna", "Doe", 30, None)
   )
//def findById(id: Int): Option[User] = users
//def findAll = users.values
def getUsers() = { users }
}

for ((k,v) <- UserRepository.getUsers() ){
 println(v)
}

Error:(25, 42) value filter is not a member of object cala.collection.immutable.Map for ((k,v) <- UserRepository.getUsers() ){

I expected that val users is holding Map ?

Simple map is working fine: 

val simpleMap = Map (1 -> "First", 2 -> "Second")

for ((k,v) <- simpleMap ){
 println(v)
}

Upvotes: 1

Views: 265

Answers (2)

Nagarjuna Pamu
Nagarjuna Pamu

Reputation: 14825

Start parenthesis immediately after Map to tell scala compiler that parenthesis belongs to Map

Instead of this 

object UserRepository {
 val users = Map
 ( 1 ->  User(1, "John", "Doe", 32, Some("male")),
   2 -> User(2, "Johanna", "Doe", 30, None)
   )
//def findById(id: Int): Option[User] = users
//def findAll = users.values
def getUsers() = { users }
}

do this 

object UserRepository {
   val users = Map( 1 ->  User(1, "John", "Doe", 32, Some("male")),
     2 -> User(2, "Johanna", "Doe", 30, None)) //start parenthesis after Map
   //def findById(id: Int): Option[User] = users
   //def findAll = users.values
  def getUsers() = { users }
}

Upvotes: 2

Alexey Romanov
Alexey Romanov

Reputation: 170733

val users = Map
( 1 ->  User(1, "John", "Doe", 32, Some("male")),
  2 -> User(2, "Johanna", "Doe", 30, None)
)

This is two separate expressions: first you do val users = Map (which is valid in Scala, and assigns the companion object of type Map to users), then evaluate

( 1 ->  User(1, "John", "Doe", 32, Some("male")),
  2 -> User(2, "Johanna", "Doe", 30, None)
)

and throw away the result. If you tell the compiler the definition isn't over yet by moving ( to the line above, it'll work:

val users = Map(
  1 ->  User(1, "John", "Doe", 32, Some("male")),
  2 -> User(2, "Johanna", "Doe", 30, None)
)

Upvotes: 6

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