`Struct.fromJson()` panics when it encounters `undefined` about protobuf-es

[srikrsna-buf]

Thank you for opening the issue along with a pr!

The ignoreUnknownFields setting is to ignore any extra json fields of a message which are not part of the message definition. For example given the following proto:

message Some {
    string foo = 1;
}

If the json value the we receive is:

{"foo": "...", "bar": "..."}

Then bar is the unknown field, and that is ignored.

Coming to Struct, it is part of special types called the Well Known Types, it is designed to represent any json value. undefined is not a valid json value. For example, if I try to do JSON.parse('{"foo": undefined}') even js will throw an error.

If you are using TypeScript, then the JsonValue type ensures that a valid json value is passed to the method. The intention for providing a fromJson is to typically pass the result of JSON.parse where instead of the raw json string we have the parsed object. So I'd say this is working as intended.

[thesiti92]

ok, we can work around it for now then. it would be helpful to at least have some flag to ignore the fields, or if you guys ever implement something like .toPlainObject and .fromPlainObject. We make extensive use of protobuf Structs and the current ways of manipulating them with protobuf-es are a bit cumbersome. either way thanks for the quick response!

[srikrsna-buf]

@thesiti92 Maybe toPlainMessage will be useful?

[thesiti92]

oh nice, didnt realize you guys added that. I think for structs its a bit more effed because the plain message representation still looks like {kind: <string>, value: <value>} which isnt super ergonomic to work with. This is all perhaps a consequence of using protobuf structs in typescript at all haha