Mapping a null value to JsValue

[alex88]

I've this query

var onTargetShots = events.filter(event => event.playerOptaId.inSet(players) && (event.eventType === 15 || event.eventType === 16))
var offTargetShots = events.filter(event => event.playerOptaId.inSet(players) && (event.eventType === 13 || event.eventType === 14))

val data = onTargetShots.map(event => (event.posX, event.posY, (event.qualifiers +> "140"), (event.qualifiers +> "141"), "on-target")).unionAll(offTargetShots.map(event => (event.posX, event.posY, (event.qualifiers +> "140"), (event.qualifiers +> "141"), "off-target")))

db.run(data.result)

and I get this slick issue:

SlickException: Read NULL value (null) for ResultSet column <computed>

looking at the code:

object SpecializedJdbcResultConverter {
  /** Create a new type-specialized `BaseResultConverter` for the given type-specialized `JdbcType` */
  def base[T](ti: JdbcType[T], name: String, idx: Int) = (ti.scalaType match {
    case ScalaBaseType.byteType => new BaseResultConverter[Byte](ti.asInstanceOf[JdbcType[Byte]], name, idx)
    case ScalaBaseType.shortType => new BaseResultConverter[Short](ti.asInstanceOf[JdbcType[Short]], name, idx)
    case ScalaBaseType.intType => new BaseResultConverter[Int](ti.asInstanceOf[JdbcType[Int]], name, idx)
    case ScalaBaseType.longType => new BaseResultConverter[Long](ti.asInstanceOf[JdbcType[Long]], name, idx)
    case ScalaBaseType.charType => new BaseResultConverter[Char](ti.asInstanceOf[JdbcType[Char]], name, idx)
    case ScalaBaseType.floatType => new BaseResultConverter[Float](ti.asInstanceOf[JdbcType[Float]], name, idx)
    case ScalaBaseType.doubleType => new BaseResultConverter[Double](ti.asInstanceOf[JdbcType[Double]], name, idx)
    case ScalaBaseType.booleanType => new BaseResultConverter[Boolean](ti.asInstanceOf[JdbcType[Boolean]], name, idx)
    case _ => new BaseResultConverter[T](ti.asInstanceOf[JdbcType[T]], name, idx) {
      override def read(pr: ResultSet) = {
        val v = ti.getValue(pr, idx)
        if(v.asInstanceOf[AnyRef] eq null) throw new SlickException("Read NULL value ("+v+") for ResultSet column "+name)
        v
      }
    }
  }).asInstanceOf[ResultConverter[JdbcResultConverterDomain, T]]

seems it's trying to convert null to play.api.libs.json.JsValue.

However seems the conversion fails since it throws an exception, shouldn't it be returning a JsNull value?

[alex88]

Nevermind, adding .? at the end of the selector worked

[tminglei]

Yes, adding .? at the end is also my suggestion. :-)

[alex88]

I just thought that since the return value was set to JsValue which includes JsNull, slick-pg was going to fill the JsValue with JsNull

[tminglei]

hmm ... yes, you're right. We should enhance it.
I'll check/do it asap.

[alex88]

Not a problem, I'm just not sure if it's a slick or pg-slick responsibility. Both Option[JsValue] or JsNull are valid for null, I think it's just a matter of covering every possible cases or not.

[tminglei]

Updated, you can help check.
If no more questions, I'll release it.

[tminglei]

@alex88 when I processing #297, I noticed the null default mechanism was discarded by slick for some time. So I'd to remove it in the next release.

---

Well, that means null will be mapped to null or None instead of JsNull or Some(JsNull).