6.7.0 appears to introduce breaking changes to TypeScript tooling

[johnnyreilly]

protobuf.js version: 6.7.0

Hello!

We started experiencing failing builds this morning following the release of v6.7. With 6.7 in play we start to receive errors of this nature:

ERROR in ./src/stores/SomethingStore.ts
(66,65): error TS2345: Argument of type 'Something$Properties' is not assignable to parameter of type 'Something'.
  Property 'toObject' is missing in type 'Something$Properties'.

It looks as though the generated classes which previously contained payloads of a given type, eg Something, now contain payloads of a type like Something$Properties. This may be more correct if the payloads received only contain the properties (I don't know if this is the case). Either way, this change has broken our code as it depends upon the entities being Something rather than Something$Properties.

We're going to pin to 6.6.5 for now since that should resolve our immediate issue. But I wanted to raise it as it seems to be "breaking changes" if only from the TypeScript angle.

Also I wanted to clarify whether: the new tooling is more correct now or if this is a bug? I'm sorry that I can't share any code beyond my example code above; I'm happy to answer questions though.

Thanks for all your work!

[dcodeIO]

Relevant issue: #717

Any instance of Something should satisfy Something$Properties without issues, though. $Properties is also only used as a parameter type and not returned, so additional information on where exactly the error originates would be helpful.

[johnnyreilly]

We have the concept of a ServerMessage which contains all the possible data structures that can be sent to the client. Here's an obfuscated version:

class ServerMessage {

    /**
     * Constructs a new ServerMessage.
     * @exports MyNamespace.ServerMessage
     * @constructor
     * @param {MyNamespace.ServerMessage$Properties=} [properties] Properties to set
     */
    constructor(properties?: MyNamespace.ServerMessage$Properties);

    /**
     * ServerMessage Somethings.
     * @type {Array.<MyNamespace.Something$Properties>|undefined}
     */
    public Somethings?: MyNamespace.Something$Properties[];

    // ...
}

You can hopefully see that the nested entities are returned as Something$Properties. Is that intentional?

This upsets the TypeScript compiler which is expecting a Something which has methods etc on it such as toObject that it may want to use.

[dcodeIO]

You can hopefully see that the nested entities are returned as Something$Properties. Is that intentional?

Ah, yes, that is intentional. When creating a message, submessages can be plain objects and hence are not necessarily an instance of the message class. The README now covers this in more detail (see also: Valid Message).

[johnnyreilly]

OK. So can we rely upon the $Properties suffix not changing in future (semver allowing)? If so then it would probably make sense to replace all our functions that receive the Something entity (in the case of nested entities) with Something$Properties instead. (If you see what I mean.)

[dcodeIO]

This now gives you an option --force-message to force documentation to reference actual message types instead of $Properties where applicable. It's still a bit stricter than before:

$Properties is still there for the constructor and .create, but it now also enforces the provided plain object to exclusively contain actual instances instead of $Properties, which is a requirement to be able to document field types as actual message types instead of $Properties (the constructor and .create just copy those over).

Hence, with --force-message, the new type checking is merely an improvement over 6.6.5, while it is a breaking change without.

[johnnyreilly]

Thanks @dcodeIO - I'll give it a try!

[johnnyreilly]

Looks good - thanks for your help one again @dcodeIO! 👍

[johnnyreilly]

Actually - I there's a problem; it looks like the Long definition is no longer referenced as I get this:

ERROR in E:\Source\App\proto\proto.d.ts
(157,25): error TS2304: Cannot find name 'Long'.