scala - How to write JSON Reads for models without a matching constructor signature? -

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i have following json object:

{"values": "123,456,789"}

i'd convert json object instance of class foo following signature, using json library of play framework:

case class foo(value1: double, value2: double, value3: double)

in documentation json combinators, there examples conversions constructor signature of class matches extracted json values. if had such case, i'd have write following reads function:

import play.api.libs.json._ import play.api.libs.functional.syntax._  implicit val fooreads: reads[foo] = (   (jspath \ "values").read[string] )(foo.apply _)

however, first have split string "123,456,789"to 3 separate strings, , convert each of them double values before can create instance of class foo. how can json combinators? not able find examples that. trying pass in function literal argument not work:

// not work implicit val fooreads: reads[foo] = (   (jspath \ "values").read[string] )((values: string) => {   val array(value1, value2, value3) = values.split(",").map(_.todouble)   foo(value1, value2, value3) })

the compiler getting confused , thinks passing function (usually implicit) parameter read method. can around explicitly using reads.map instead of applicationops.apply:

implicit val fooreads: reads[foo] = {   (jspath \ "values").read[string] map { values =>     val array(value1, value2, value3) = values.split(",").map(_.todouble)     foo(value1, value2, value3)   } }

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