Play 2.3 implicit json conversion causes null pointer exception

Question

I\'m trying to parse json into my case class DealFormMap

case class DealFormMap(limit: Option[Int], filter: Option[DealFormFilterMap])
case clas         


        

Answer 1

The problem is the order as mentioned by LimbSoup. But it's worth noting that with using Json macros you can achieve the same result with

import play.api.libs.json._

implicit val dealFormFilterMapReads: Reads[DealFormFilterMap] = Json.reads[DealFormFilterMap]

implicit val dealFormMapReads: Reads[DealFormMap] = Json.reads[DealFormMap]

Note that by using this macros, if you change the order

implicit val dealFormMapReads: Reads[DealFormMap] = Json.reads[DealFormMap]

implicit val dealFormFilterMapReads: Reads[DealFormFilterMap] = Json.reads[DealFormFilterMap]   

you will get the following helpful warning:

 Reference to uninitialized value dealFormFilterMapReads
[warn] implicit val dealFormMapReads: Reads[DealFormMap] = Json.reads[DealFormMap]
[warn]                                                                 ^
[warn] one warning found

which you can fix (again as mentioned by LimpSoup) by making dealFormFilterMapReads lazy or reordering which makes more sense in this case.

Disclaimer

Using Json macro inception in play needs Scala 2.10 and is supported on Play versions after 2.1.0