How to pass StructType between .NET & JVM?

[GoEddie]

For FeatureHasher I need to take a StructType and pass it over to the JVM as a parameter (https://spark.apache.org/docs/2.4.0/api/java/org/apache/spark/ml/feature/FeatureHasher.html#transformSchema-org.apache.spark.sql.types.StructType-).

At the moment I get "System.NotSupportedException : Type Microsoft.Spark.Sql.Types.StructType not supported yet".

Is the way to implement it to serialise/deserialise as json across the wire or is there a better way? StructType already has a constructor from json and a json value to get the json from it on the .NET side.

I'm not sure if I am missing something because shouldn't it just be treated like any other jvm object reference?

[Niharikadutta]

I am working on adding support to pass StructType between .NET and JVM as a part of #649 . You should be able to just use it once that is in. Thanks!

[GoEddie]

Great, i'll leave that method off until 649 is ready.

[suhsteve]

I'm pretty sure we solved this already. You should use

spark/src/csharp/Microsoft.Spark/Sql/Types/DataType.cs

Lines 89 to 95 in 9239e72

	internal static JvmObjectReference FromJson(IJvmBridge jvm, string json)
	{
	return (JvmObjectReference)jvm.CallStaticJavaMethod(
	"org.apache.spark.sql.types.DataType",
	"fromJson",
	json);
	}

Please see this example

spark/src/csharp/Microsoft.Spark/Sql/DataFrameReader.cs

Lines 49 to 53 in 9239e72

	public DataFrameReader Schema(StructType schema)
	{
	_jvmObject.Invoke("schema", DataType.FromJson(_jvmObject.Jvm, schema.Json));
	return this;
	}

[GoEddie]

got it, thanks