Scala case class Option value chaining

scala option get
scala option[string]
scala option fold
getorelse scala map
option usage in scala
scala option
option's and traits in scala
scala trait option
case class Person(@BsonProperty("first_name") firstName:Option[String],@BsonProperty("second_name")  secondName:Option[String],@BsonProperty("person_age") var  age:Int)


val me = Some(Person(Some(Ambareesh),Some(B),23))

      Or

val me = None

      Or

val me = Some(Person(Some(Ambareesh),None,23))

     Or

val me = Some(Person(None,None,23))


someOperation(me.secondName / None) //How can I implement this behavior in single line.
someOperation(me.firstName / None)


def someOperation(name:Option[String]){
   //Do ...
 }

My doubt regarding the argument (instance of Person) to method someOperation. The argument itself is an Option value and fields are also Options. If either of this is None(argument or argument.fieldName) I want None as return else the field value as Some(fieldValue). Is it possible?

someOperation(me.flatMap(_.secondName))

See ScalaDoc.

You can use map for non-Option properties: me.map(_.age) is Option[Int].

Scala case class Option value chaining - scala - html, Returning an Option from a method; Getting the value from an Option; Using scala> bag.map(toInt).collect{case Some(i) => i} res3: List[Int] = List(1, 2, 3) The Try class has the added benefit that you can chain operations  Self Type Option[A] Source Option.scala Version. 1.1, 16/01/2007 Note. Many of the methods in here are duplicative with those in the Traversable hierarchy, but they are duplicated for a reason: the implicit conversion tends to leave one with an Iterable in situations where one could have retained an Option.

If your someOperation returns an Option that you could also use a for comprehension.

val result: Option[String] = for {
   person <- me
   firstName <- someOperation(person.firstName)
   secondName<- someOperation(person.secondName)
} yield <use firstName, secondName here>

This will give you whatever result you want to calculate or None.

Scala best practice: How to use the Option/Some/None pattern , This allows for sophisticated chaining of Option values without having to check for the A less-idiomatic way to use Option values is via pattern matching: We need a whole WithFilter class to honor the "doesn't create a new collection"  scala> val x = toInt("1") x: Option[Int] = Some(1) This is what it looks like when it fails and returns a None: scala> val x = toInt("foo") x: Option[Int] = None Getting the value from an Option. The toInt example shows how to declare a method that returns an Option.

As I understood, you need to extract person fields and pass it into the method someOperation. Right?

If so, you can use pattern matching for this:

someOperation(
  me match {
    case Some(person) => person.firstName
    case None => None
  } 
)

scala.Option, sealed abstract class Option[+A] extends Product with Serializable This allows for sophisticated chaining of Option values without having to check for the existence of a value. toUppercase) } case None => { println("No name value") } }. Returns a scala.Some containing the result of applying pf to this scala.Option's contained value, if this option is nonempty and pf is defined for that value. Returns a scala.Some containing the result of applying pf to this scala.Option 's contained value, if this option is nonempty and pf is defined for that value.

Scala Standard Library 2.13.2, sealed abstract class Option[+A] extends IterableOnce[A] with Product with Serializable This allows for sophisticated chaining of scala.Option values without having to check for the existence of a value. val nameMaybe = request getParameter "name" nameMaybe match { case Some(name) => println(name.​trim. Scala Option[ T ] is a container for zero or one element of a given type. An Option[T] can be either Some[T] or None object, which represents a missing value. For instance, the get method of Scala's Map produces Some(value) if a value corresponding to a given key has been found, or None if the given key is not defined in the Map.

Using Option in Scala, Part 3: for-comprehension, Chain optional values together using for-comprehension. case class Student(id​: Long, name: String, tutor: Option[Professor]) case class  Step 3: Chaining Future Option using for comprehension checking donut stock buying 10 donuts Buying vanilla donut was successful = true Future option with map. In this example, we will show how you can access the value wrapped inside a Future of Option using the map function.

Using Option in Scala, Part 2: map and flatmap, You're going to learn how to transform an optional value using map. You'll case class Car(model: String, owner: Option[Person], registrationPlate: Option[String]) case class Listing 8: Chaining optional values with flatMap. Case Classes. Case classes are like regular classes with a few key differences which we will go over. Case classes are good for modeling immutable data. In the next step of the tour, we’ll see how they are useful in pattern matching.

Comments
  • I am sorry. I couldnt understand the question
  • val me = Some(Person(Some(Ambareesh),Some(B),23)). me.get.firstName.get should return None / firstName i.e Option[String] similarly me.get.secondName.get. I have more parameters like firstName and secondName so I should able to refer it in the function call itself.
  • Isn't me.firstName already an Option?
  • @Jatin No, me.firstName doesn't compile.
  • yes me.get.firstName will work if me is not None.
  • but me can be None. I have edited the question clarify this.
  • Yes and that makes no difference to the for comprehension and you'll just get None in the end. Using either this or any of the other answers is just a matter of style as there are many ways to solve this problem.