Option in the Scala language is a container for zero or one element of a given type.
Option in scala is a container for zero or one element of a given type.
Questions tagged [scala-option]
232 questions
1
vote
1 answer
How to generate json string if the `Json.obj` contains a `None` value?
In playframework:
import play.api.libs.json._
val obj = Json.obj(
"aaa" -> 111,
"bbb" -> Some(222)
)
println(obj.toString)
Which outputs:
{"aaa":111,"bbb":222}
But if I change the code to:
val obj = Json.obj(
"aaa" -> 111,
"bbb" ->…
Freewind
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1
vote
3 answers
Override toString behavior for Option[_] in scala
I would prefer to see just the value of the Option (if it were not None) , instead of the following additional Some() noise:
List((Some(OP(_)),Some(share),3), (Some(OP(D)),Some(shaara),4), (Some(OP(I)),Some(shaaee),4))
Now, I could write a method…
WestCoastProjects
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1
vote
3 answers
Scala Option ||
I want to get the value of one of several Option in scala, like this:
def or(a:Option[Int], b:Option[Int]):Option[Int]=
if (a.isDefined) a else b
val a= Option(1)
val b= Option(2)
or(a,b).get
but I wonder why isn't the || operator defined for…
loopbackbee
- 21,962
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1
vote
1 answer
How to retrieve an Option[List[X]] instead of List[X] from a select statement in Play2!Scala Anorm?
In my Play2 app, I am trying to retrieve a list of users from one of my database table. The query responsible for this may potentially be empty if there is no row in the database matching the criteria (which is the firstName in our case). That is…
kaffein
- 1,766
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0
votes
5 answers
Processing Scala Option[T]
I have a Scala Option[T]. If the value is Some(x) I want to process it with a a process that does not return a value (Unit), but if it is None, I want to print an error.
I can use the following code to do this, but I understand that the more…
Ralph
- 31,584
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0
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3 answers
scala: updating string value in an option
I have an Option of a string. I want to update the contained value:
if(x.isEmpty) {
...another calculation
} else {
x.map(val => ...update val)
}
Is this an idiomatic way?
Mandroid
- 6,200
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0
votes
1 answer
Subtracting two Option[Double]
I have two variables that are optional double and I want to consider them as 0 when they are None
var x: Option[Double] = Option(0)
var y: Option[Double] = Option(0)
println("Expected 0 : "+(x ++ y).reduceOption(_ - _)) // 0
x = Option(4)
y =…
Ranveer Singh
- 27
- 1
- 7
0
votes
1 answer
Scala Option: Usage of unless with getOrElse
I have an Option of string, say O, which can be empty. And there is a condition, say cond. My requirement is to construct Option of the value inside O if cond is true, else None.
I do this:
Option.unless(cond)(o.getOrElse(None))
Is this a correct…
Mandroid
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- 134
0
votes
0 answers
OutOfMemory error at option2Iterable in scala
I am converting list of strings to list of BigDecimal values in below scala code.
But when queryResults list is very large (> 10 million), I'm getting below error.
We have some limitations on memory usage and cannot increase memory. Is there any way…
Ankitha Vaddeti
- 1
- 3
0
votes
1 answer
Extract Option from Future in ActionBuilder
I am implementing authentication based on this Scala Play Authentication example.
Therefore I use the following ActionBuilder to build an UserAction.
UserAction.scala
class UserRequest[A](val user: Option[Admin], request: Request[A]) extends…
tomole
- 927
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- 35
0
votes
1 answer
Scala. How to Unmarshall Option values using json spray?
I'm using json-spray library to unmarshall a json array.
Here is the code.
import akka.http.scaladsl.marshallers.sprayjson.SprayJsonSupport._
import spray.json.DefaultJsonProtocol._
def unmarshalProfiles(response: HttpResponse):…
Salvatore Calcagno
- 135
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- 8
0
votes
1 answer
Whats the best way of getting a list of a field from a object?
So right now I have a list of a object with a Optional Field like this in scala
case class Foo(
id: String,
description: String,
OptionalTag: Option[String],
)
What I want is to iterate…
Mylies
- 396
- 4
- 18
0
votes
2 answers
Determine non-empty additional fields in a subclass
Assume I have a trait which looks something like this
trait MyTrait {
val x: Option[String] = None
val y: Option[String] = None
}
Post defining the trait I extend this trait to a class MyClass which looks something like this
case class…
Rakshith
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0
votes
2 answers
find method in scala's collection
Per the documentation, find function in scala's collection wraps the resulting elements in Option object. In the below, the size operation ends in error; where as the endsWith produces correct result.
The second element in the list being null, both…
user3103957
- 636
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0
votes
2 answers
Process Scala Option type with higher-order functions
There is a class
class MyType {
def status(): String = "Connected" // demo implementation
}
I have a val x: Option[Option[MyType]]. I need to process this value like the following:
x match {
case None => "Error1"
case Some(None) => "Error2"
…
Loom
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