CODEWITHSUNDEEP
scalajson4s
igreenfield
igreenfield

Reputation: 1702

Deserializing Option returns None instead of an exception in json4s

When running the following code I would expect an exception, but I get None instead. Is that expected? 

import org.json4s.jackson.JsonMethods
import org.json4s.{DefaultFormats, Formats}
implicit val f: Formats = DefaultFormats
val json ="{ \"a\" : { \"c\": 1 }}"

case class Foo(a: Option[String])
val foo = JsonMethods.parse(json).extract[Foo]

println(foo)

>  Foo(None)

also that code:

import org.json4s.jackson.JsonMethods
import org.json4s.{DefaultFormats, Formats}
implicit val f: Formats = DefaultFormats
val json ="{ \"a\" : { \"c\": 1 }}"

case class Foo(a: String = "")
val foo = JsonMethods.parse(json).extract[Foo]

println(foo)

>  Foo()

Upvotes: 5

Views: 523

Answers (1)

Szymon Jednac
Szymon Jednac

Reputation: 3007

You can enforce strict option parsing by changing the default format as such:

implicit val f: Formats = DefaultFormats.withStrictOptionParsing

The underlying exception:

[error] (run-main-2) org.json4s.package$MappingException: No usable value for a
[error] Do not know how to convert JObject(List((c,JInt(1)))) into class java.lang.String

Upvotes: 5

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