Scala: How to create a case class with multiple alternate constructors

By Alvin Alexander. Last updated: December 17, 2020

As a brief note today, if you want to see how to create a Scala case class that defines multiple alternate constructors, I hope this example is helpful:

package models

import java.util.Date

// PRIMARY CONSTRUCTOR
case class Url (
    id: Long,
    longUrl: String,
    shortUrl: String,
    notes: String,
    dateCreated: Date,
    numClicks: Long
)

object Url {

    // ALTERNATE CONSTRUCTOR #1 (without numClicks)
    def apply(
        id: Long,
        longUrl: String,
        shortUrl: String,
        notes: String,
        dateCreated: Date,
    ): Url = {
        Url(id, longUrl, shortUrl, notes, dateCreated, 0)
    }

    // ALTERNATE CONSTRUCTOR #2 (without dateCreated or numClicks)
    def apply(
        id: Long,
        longUrl: String,
        shortUrl: String,
        notes: String
    ): Url = {
        Url(id, longUrl, shortUrl, notes, new Date(), 0)
    }

    // this is for something else, but i left it here as an `unapply` example
    def unapply(u: Url): Option[(Long, String, String, String)] = {
        Option(
            u.id,
            u.longUrl,
            u.shortUrl,
            u.notes
        )
    }
}

With that case class defined as shown, you can create new case class instances in the following ways:

val u = Url(id, longUrl, shortUri, notes, dateCreated, numClicks)
val u = Url(id, longUrl, shortUri, notes, dateCreated)
val u = Url(id, longUrl, shortUri, notes)

If you needed to see an example of a case class in Scala with multiple constructors, I hope that helps.

scala

class