Generate TypeScript event name -> message type map

trevordixon commented 1 year ago

Reason/Context

Please try answering few of those questions

Why we need this improvement?
How will this change help?
What is the motivation?

I'd like TypeScript to be able to verify that I'm associating the correct message type with a channel. Modelina could generate a type map, e.g.:

type ChannelToMessageType = {
  'foo.bar': FooBarMessage,
  'bar.baz': BarBazMessage,
}

This type could then be used to write safer code where TypeScript would ensure channels and message types match.

function pub<C extends keyof ChannelToMessageType>(channel: C, payload: ChannelToMessageType[C]) {
}

Description

Please try answering few of those questions

What changes have to be introduced?
Will this be a breaking change?
How could it be implemented/designed?

Not sure about this. I'd take a crack at implementing it if I could get a few pointers.

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jonaslagoni commented 1 year ago

Hey @trevordixon, thanks for the issue!

By using the https://modelina.org/examples?selectedExample=asyncapi-from-parser and https://modelina.org/examples?selectedExample=meta-model you can pretty easily assemble this yourself 🙂

Here is some pseudo code to get you started:

const customModel = new ObjectModel('ChannelToMessageType', undefined, {});
for (channel in asyncapi.channels()) {
  const messageType = FormatHelpers.toPascalCase(channel.publish().message().payload().uid());
  const refModel = new ReferenceModel(messageType, undefined, {}, new ObjectModel(messageType, undefined, {}))
  const propertyModel = new ObjectPropertyModel(
    refModel.name,
    false,
    refModel
  );
  customModel.properties[propertyModel.propertyName] = propertyModel;
}
const inputModel = new InputMetaModel();
inputModel.models[customModel.name] = customModel;

... generator.generate(inputModel);

This means 15 lines of code and you have the model in all languages (just use different generators) 🙂

Whether this is something we want part of the native AsyncAPI input processor, not sure 🤔 Similar issues are https://github.com/asyncapi/modelina/issues/181 and https://github.com/asyncapi/modelina/issues/982

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github-actions[bot] commented 1 month ago