spark custom kryo encoder not providing schema for UDF

问题

When following along with How to store custom objects in Dataset? and trying to register my own kryo encoder for a data frame I face an issue of Schema for type com.esri.core.geometry.Envelope is not supported

There is a function which will parse a String (WKT) to an geometry object like:

def mapWKTToEnvelope(wkt: String): Envelope = {
    val envBound = new Envelope()
    val spatialReference = SpatialReference.create(4326)
    // Parse the WKT String into a Geometry Object
    val ogcObj = OGCGeometry.fromText(wkt)
    ogcObj.setSpatialReference(spatialReference)
    ogcObj.getEsriGeometry.queryEnvelope(envBound)
    envBound
  }

This is applied to an UDF like:

implicit val envelopeEncoder: Encoder[Envelope] = Encoders.kryo[Envelope]
val ST_Envelope = udf((wkt: String) => mapWKTToEnvelope(wkt))

However, the UDF will compile but throw a runtime error of:

[error] Exception in thread "main" java.lang.UnsupportedOperationException: Schema for type com.esri.core.geometry.Envelope is not supported
[error]         at org.apache.spark.sql.catalyst.ScalaReflection$.schemaFor(ScalaReflection.scala:733)
[error]         at org.apache.spark.sql.catalyst.ScalaReflection$.schemaFor(ScalaReflection.scala:671)
[error]         at org.apache.spark.sql.functions$.udf(functions.scala:3076)

edit

Whereas

val first = df[(String, String)].first
val envBound = new Envelope()
val ogcObj = OGCGeometry.fromText(first._1)
ogcObj.setSpatialReference(spatialReference)
ogcObj.getEsriGeometry.queryEnvelope(envBound)
spark.createDataset(Seq((envBound)))(envelopeEncoder)

Works just fine:

root
 |-- value: binary (nullable = true)
+--------------------+
|               value|
+--------------------+
|[01 00 63 6F 6D 2...|
+--------------------+

How can I get it to work in the UDF as well

来源：https://stackoverflow.com/questions/44735235/spark-custom-kryo-encoder-not-providing-schema-for-udf