Given a json:
val json = """
{
"persons": [
{"name": "Foo", "age": 21},
{"name": "Bar", "age": 22},
{"name": "Baz", "age": 23}
]
}
"""
How to construct a play Reads[List[String]] which will extract list of names form that json?
import play.api.libs.json._
val reads: Reads[List[String]] = ???
val names: List[String] = reads.reads(Json.parse(json))
// expecting List("Foo", "Bar", "Baz")
Could try the workaround?
final case class Person(name: String, age: Int)
object Person {
implicit val PersonFormat = Json.format[Person]
}
val jsonStr= """
{
"persons": [
{"name": "Foo", "age": 21},
{"name": "Bar", "age": 22},
{"name": "Baz", "age": 23}
]
}
"""
(Json.parse(jsonStr) \ "persons").as[List[Person]].map(p => p.name)
Or
((Json.parse(jsonStr) \ "persons") \\ "name").map(_.as[String])
Reads, not a JsResult + .as[T] is unsafe
Just compose with Reads.
import play.api.libs.json._
val input = Json.parse("""
{
"persons": [
{"name": "Foo", "age": 21},
{"name": "Bar", "age": 22},
{"name": "Baz", "age": 23}
]
}
""")
val nameReads = (JsPath \ "name").read[String]
val listReads: Reads[Seq[String]] = Reads.seq(nameReads)
(input \ "persons").validate(listReads)
// JsSuccess(Vector(Foo, Bar, Baz),)
How to construct a play Reads[List[String]]. My edit to your response provided this information, shame that you have rejected it...