AVRO - Complex Records with Union Record type support

Question

I am trying to build an AVRO's complex record with Union data type supported member record type.

{
    "namespace": "proj.avro",
    "protocol": "app_messages",
    "doc" : "application messages",
    
    "types": [
        {
            "name": "record_request",
            "type" : "record", 
            "fields": 
            [
                {
                    "name" : "request_id", 
                    "type" : "int"
                },
                {
                    "name" : "message_type",
                    "type" : int,
                },
                {
                    "name" : "users",
                    "type" : "string"
                }
            ]
        },
        {
            "name" : "request_response",
            "type" : "record",
            "fields" :
            [
                {
                    "name" : "request_id",
                    "type" : "int"
                },
                {
                    "name" : "response_code",
                    "type" : "string"
                },
                {
                    "name" : "response_count",
                    "type" : "int"
                },
                {
                    "name" : "reason_code",
                    "type" : "string"
                }
            ]
        }
    ]
    
    "messages" :
    {
        "published_msgs" :
        {
            "doc" : "My Messages",
            "fields" :
            [
                {
                    "name" : "message_type",
                    "type" : "int"
                },
                {
                    "name" : "message_body",
                    "type" : 
                    [
                        "record_request", "request_response"
                    ]
                }
            ]
            
        }
    }
}

I am getting error while trying to read this kind of schema.

I would like to know - is it possible to declare such AVRO schema - which has one of field which type is union of complex user defined message structure.

If its possible then could you please let me know what i am doing wrong or an example of such structure with union type field's type definition?

I want to use AVRO's dynamically schema usage - so specify this schema file run-time and parse the incoming buffer as "request"/"response".

Thanks,

Answer 1

It is possible define an union of complex types, the problem with your schema is that it is not defined at field level. Your schema must looks like this to achieve the union of complex types

{
    "namespace": "proj.avro",
    "protocol": "app_messages",
    "doc" : "application messages",
    "name": "myRecord",
    "type" : "record",
    "fields": [
    {
    "name": "requestResponse",
    "type": [
        {
            "name": "record_request",
            "type" : "record", 
            "fields": 
            [
                {
                    "name" : "request_id", 
                    "type" : "int"
                },
                {
                    "name" : "message_type",
                    "type" : "int"
                },
                {
                    "name" : "users",
                    "type" : "string"
                }
            ]
        },
        {
            "name" : "request_response",
            "type" : "record",
            "fields" :
            [
                {
                    "name" : "request_id",
                    "type" : "int"
                },
                {
                    "name" : "response_code",
                    "type" : "string"
                },
                {
                    "name" : "response_count",
                    "type" : "int"
                },
                {
                    "name" : "reason_code",
                    "type" : "string"
                }
            ]
        }
    ]
    }
    ]
}