For the JSON RPC library I wanted to supported dynamic arrays but in order to do this I needed to duplicate TJSONStreamer's ObjectToJSON and StreamProperty in order to bypass some exceptions. If StreamProperty was virtual I could simply override that and stream the dynamic arrays before calling inherited.

What do you think about that?

Regards,
Ryan Joseph

Hairy Pixels wrote

For the JSON RPC library I wanted to supported dynamic arrays but in order to do this I needed to duplicate TJSONStreamer's ObjectToJSON and StreamProperty in order to bypass some exceptions. If StreamProperty was virtual I could simply override that and stream the dynamic arrays before calling inherited. What do you think about that?

It would be a much better idea to implement the streaming of dynamic arrays directly. Then the exceptions are maybe not necessary in the first place...

Michael.

Small follow-up:

If you want to extend it, you can find the necessary code in the restbase unit. It already implements the necessary code to (de)stream arrays, plus some other enhancements as well. It's on my TODO list to merge the implementations taking TJSONStreamer as a base, but if you are busy with this maybe you can provide a patch...

Michael.

I probably don’t know enough about the library to do this well or quickly enough. This is what I hacked together but it only works on the 2 array types I need and I may not have done this correctly even.

function TLSPStreamer.StreamProperty(Const AObject: TObject; PropertyInfo: PPropInfo): TJSONData;
type
  TVariantArray = array of Variant;
  TObjectArray = array of TObject;
var
  PropArray: TJSONArray;
  ElementType: PTypeInfo;
  VariantArray: TVariantArray;
  ObjectArray: TObjectArray;
  i: integer;
begin
  Result := nil;
  if PropertyInfo^.PropType^.Kind = tkDynArray then
    begin
      // Class kinds are in ElType2 (not sure why)
      ElementType := GetTypeData(PropertyInfo^.PropType)^.ElType;
      if ElementType = nil then
        ElementType := GetTypeData(PropertyInfo^.PropType)^.ElType2;
      PropArray := TJSONArray.Create;
      case ElementType^.Kind of
        tkVariant:
          begin
            VariantArray := TVariantArray(GetDynArrayProp(AObject, PropertyInfo));
            for i := 0 to High(VariantArray) do
              PropArray.Add(StreamVariant(VariantArray[i]));
            Result := PropArray;
          end;
        tkClass:
          begin
            ObjectArray := TObjectArray(GetDynArrayProp(AObject, PropertyInfo));
            for i := 0 to High(ObjectArray) do
              PropArray.Add(StreamClassProperty(ObjectArray[i]));
            result := PropArray;
          end;
        otherwise
          raise EUnknownErrorCode.Create('Dynamic array element type "'+Integer(ElementType^.Kind).ToString+'" is not supported for responses.');
      end;
    end
  else
    Result := inherited StreamProperty(AObject, PropertyInfo);
end;

Regards,
Ryan Joseph