We already have flatbuffer library embedded in our software code for simple schemas with JSON output data generation.

Now we also need to have the following schema tree to be supported.

namespace SampleNS;
/// user defined key value pairs to add custom metadata
/// key namespacing is the responsibility of the user
table KeyValue {
 key:string (key, required); 
 value:string (required);
}
enum SchemaVersion:byte {
 V1,
 V2
}
table Sometable {
 value1:ubyte;
 value2:ushort (key);
}
table ComponentData {
 inputs: [Sometable];
 outputs: [Sometable];
}
table Node {
 name:string (key);
 
 /// IO definition
 data:ComponentData;
 
 /// nested child
 child:[Components];
}
table Components {
 type:ubyte;
 index:ubyte;
 nodes:[Node];
}
table GroupMasterData {
 schemaversion:SchemaVersion = sampleNS::SchemaVersion::V1;
 metainfo:[KeyValue];
 /// List of expected components in the system
 components:[Components];
}
root_type GroupMasterData;

As from above, table Components is nested recursively. The intention is components may have childs that have the same fields.

I have few queries:

• Flatc didnt gave me any error during schema compilation for such
  recursive nested tables. But is this supported during the field
  access for such tables?
• I tried to generate a sample json data file based on above data but I
  could not see the field for schemaversion. I learned FB doesn't
  serialize the default values. so, I removed the default value that I
  assigned in the schema. But, it still doesnt write into the json data
  file. On this I also learned we can forcefully write into the file
  using force_defaults option. I don't know where is this is to be
  put: in the attribute or elsewhere?
• Can I create a struct of enum field?