Major Description
Currently, when deserializing protobufs using from_protobuf, fields that are not explicitly present in the serialized message are deserialized as null in the resulting struct. However this includes singular proto3 scalars set explicitly to their default values, as they will not appear in the serialized protobuf.
For example, given a message format like
syntax = "proto3";
message Person {
string name = 1;
int64 age = 2;
optional string middle_name = 3;
optional int64 salary = 4;
}
and an example message like
SearchRequest(age = 0, middle_name = "")
the result from calling from_protobuf on the serialized form of the above message would be
{"name": null, "age": null, "middle_name": "", "salary": null}
It can be useful to deserialize these fields as their defaults, e.g.:
{"name": "", "age": 0, "middle_name": "", "salary": null}
This behavior also exists in other major libraries, e.g.
- java's jsonformat `includingDefaultValues` https://protobuf.dev/reference/java/api-docs/com/google/protobuf/util/JsonFormat.Printer.html#includingDefaultValueFields--
- golang's jsonpb `emitDefaults` https://pkg.go.dev/github.com/golang/protobuf/jsonpb#Marshaler
I propose extending the spark-protobuf library to support this behavior.
