How to use Apache Geode type registry to write arrays of domain objects

Question

I am working on a FIX repeating group where a quote request can have x legs. I have made a Leg class like this:

public class Leg : IPdxSerializable
{
  public string Side { get; set; }
  public decimal Size { get; set; }
  public string ValueDate { get; set; }

  public void ToData(IPdxWriter writer)
  {
    writer.WriteString("Side", Side);
    writer.WriteDouble("Size", Convert.ToDouble(Size));
    writer.WriteString("ValueDate", ValueDate);
  }

  public void FromData(IPdxReader reader)
  {
    Side = reader.readString("Side");
    Size = (decimal) reader.ReadDouble("Size");
    ValueDate = reader.readString("ValueDate");
  }

  public static IPdxSerializable CreateDeserializable()
  {
    return new Leg();
  }

  public Leg () { }
}

The legs for a quote request are written as an array of these Leg objects. In the quote request class there is a Leg[] declaration and ToData FromData implementation. The quote request object is built and put into a Geode region as a PDX Type, in which the array of legs is written by the PDX Writer as:

writer.WriteObjectArray("Legs", Legs.ToList<object>());

I have tried different types for the List of Leg as both PDX type and domain object type, but when I get the object in GFSH the leg array has given flavours of errors like:

Could not create an instance of a class Leg (through reference chain: org.apache.geode.pdx.internal.PdxInstanceImpl[0]->org.apache.geode.pdx.internal.PdxInstanceImpl["object"])

or

Could not create an instance of a class Leg (through reference chain: java.util.Vector[0]->org.apache.geode.pdx.internal.PdxInstanceImpl["object"])

I thought this was because the Geode server has not had a Leg object type registered in the server's TypeRegistry. Since Geode version 10 of the native client there is no longer a Serializable.RegisterPdxType which was used like this:

Serializable.RegisterPdxType(Leg.CreateDeserializable);

I have found the TypeRegistry class reference and on initializing the cache and regions also register the type into the cache:

_cache.TypeRegistry.RegisterPdxType(Leg.CreateDeserializable);

but still get the same error.

It's the same error if an array of Legs is written merely as an object

writer.WriteObject("Legs", Legs);

If I convert the Leg object into a string[] representation this is working fine with either WriteStringArray and ReadStringArray as a quote request where the Legs are an array of strings, but that has it's own problems, I want to use an array of Leg objects, preferably PDX wrapped. What am I missing?

Answer 1

rupweb you can just use:

output.WriteObject(LEGS_KEY_, Legs);

and

Legs = (Leg[])input.ReadObject(LEGS_KEY_);

instead of WriteObjectArray/ReadObjectArray. Not sure what the limitations are on these. Still investigating.