Typed Custom Events

[tsteckenborn]

Hey there,

it would be great to enhance the type safety when working with events.

Given a sample with two services (A and B), if an event is defined in service A, such as:

        event SomeService.SomeEvent : {
            ID        : SomeEntity:ID;
            }

and e.g. consumed in service B, such as:

import SomeService, {
 SomeEvent,
} from '#cds-models/SomeService';

//...

export default class SomeOtherService extends cds.ApplicationService {
 override async init() {
// ...
  const someService = await cds.connect.to(SomeService);
  someService.on(SomeEvent, async (msg) => {
   console.log(msg.data);
  });
// ...

then msg (or msg.data) or not yet typed. The properties are eventually available in the class, yet not "exposed" in that kind of usage.

Br,
Tobias

[tsteckenborn]

Closing as this is likely rather typer, not types. (see cap-js/cds-typer#579)

// Moved back here, as likely rather types.

[tsteckenborn]

Seems to extend to more areas, as e.g. also:

				await this.emit(SomeEvent, {
// ...
				});

the payload is defined as (parameter) data: object | undefined.

[tsteckenborn]

Not sure if that's then typer, but for the generated elements, it might also depend on the format. E.g. CloudEvents (configuration option) might add some headers. Could be good to already indicate these.