scala call constructor of case class with all fields except one automatically

Question

I am curious how to call the constructor of a scala case class with all of its fields except one (automatically)

case class MyClass(a:String, b:Int, c:String)
val myThing = MyClass("a", 1, "b")

Something like MyClass("someOtherValue", myThing.getAllTheValuesExceptOne: _*) did not yet work for me.

That is not yet clear to implement that properly ( without writing all the columns) as the class has a lot of fields. — Georg Heiler, Jan 25 '17 at 10:35
possible duplicate of http://stackoverflow.com/questions/7249396/how-to-clone-a-case-class-instance-and-change-just-one-field-in-scala — oblivion, Jan 25 '17 at 16:58

vvg · Accepted Answer · 2017-01-25T11:08:38.087

8

You can use copy method of case classes, it allows to create case class based on others overriding some particular fields.

case class MyClass(a:String, b:Int, c:String)
val myThing = MyClass("a", 1, "b")
val myThing2 = myThing.copy(a = "someOtherValue")

edited Jan 25 '17 at 11:08

answered Jan 25 '17 at 10:37

vvg

score 1 · Answer 2 · answered Jan 25 '17 at 13:04

1

Another option is to create a companion object with an apply method.

object MyClass {
  def apply(a: String) = {
    new MyClass(a, 1, "AAA")
  }
}

Then you can just use

val newInstance = MyClass("BBB")

answered Jan 25 '17 at 13:04

Vod

The question is looking for some `automatic` way. This is way too manual approach specially if you have a lot of fields. – oblivion Jan 25 '17 at 16:55

2 Answers2