Reading multiple variables from an object wrapped in Option[]
-
23-12-2020 - |
Question
I have a variable obj: Option[MyObject]
and want to extract multiple variables from it - if the object is not set, default values should be used.
Currently I do it like this:
val var1 = obj match {
case Some(o) => e.var1
case _ => "default1"
}
val var2 = obj match {
case Some(o) => e.var2
case _ => "default2"
}
...
which is extremely verbose. I know I could do it like this:
val var1 = if (obj.isDefined) obj.get.var1 else "default1"
val var2 = if (obj.isDefined) obj.get.var2 else "default2"
which still seems strange. I know I could use one big match and return a value object or tuple.
But what I would love is something similar to this:
val var1 = obj ? _.var1 : "default1"
val var2 = obj ? _.var2 : "default2"
Is this possible somehow?
Solution
How about this?
obj.map(_.var1).getOrElse("default1")
or, if you prefer this style:
obj map (_ var1) getOrElse "default"
OTHER TIPS
Another variation would be to use a version of the Null Object Pattern and use the object directly
//could also be val or lazy val
def myDefault = new MyObject {
override val var1 = "default1"
override val var2 = "default2"
}
val myObj = obj getOrElse myDefault
use(myObj.var1)
use(myObj.var2)
To extract multiple values from an Option I'd recommend returning a tuple and using the extractor syntax:
val (val1, val2) = obj.map{o => (o.var1, o.var2)}.getOrElse(("default1", "default2"))
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