scala newbie having troubles with Option, what's the equivalent of the ternary operator

Question

I've already read that the if statement in scala always returns an expression

So I'm trying to do the following (pseudo code)

sql = "select * from xx" + iif(order.isDefined, "order by " order.get, "")

I'm trying with

val sql: String = "select * from xx" + if (order.isDefined) {" order by " + order.get} else {""} 

But I get this error:

illegal start of simple expression

order is an Option[String]

I just want to have an optional parameter to a method, and if that parameter (in this case order) is not passed then just skip it

what would be the most idiomatic way to achieve what I'm trying to do?

-- edit --

I guess I hurried up too much to ask

I found this way,

val orderBy = order.map( " order by " + _ ).getOrElse("")

Is this the right way to do it?

I thought map was meant for other purposes...

Answer 1

First of all you are not using Option[T] idiomatically, try this:

"select * from xx" + order.map(" order by " + _).getOrElse("")

or with different syntax:

"select * from xx" + (order map {" order by " + _} getOrElse "")

Which is roughly equivalent to:

"select * from xx" + order match {
  case Some(o) => " order by " + o
  case None => ""
}

Have a look at scala.Option Cheat Sheet. But if you really want to go the ugly way of ifs (missing parentheses around if):

"select * from xx" + (if(order.isDefined) {" order by " + order.get} else {""})

Answer 2

...or, if you really want to impress your friends:

order.foldLeft ("") ((_,b)=>"order by  " + b)

(I would still recommend Tomasz's answer, but I think this one is not included in the scala.Option cheat sheet, so i thought I'd mention it)