Model compostion and Optional Properties

[laduke]

Dealing with an existing API.

There's a model like below. Then in HTTP stuff , the POST request format is ThingWritable. The response format is Thing and the GET response is Thing.
The little issue is Thing has ThingWritable's props as Optional. They should be required there.

What's the good pattern for composing something like this?

model ThingWritable {
  prop1?: boolean;
  prop2?: boolean;
}

model Thing{
  ...ThingWritable;
  readonly1: boolean;
  readonly2: boolean;
}

[bterlson]

We have OptionalProperties<T>, though not RequiredProperties which should be added I think, so you could write:

model Thing {
    ... RequiredProperties<ThingWritable>;
}

For now, you could do something like:

alias ThingProps = {
  prop1: boolean;
  prop2: boolean;
}

model ThingWritable {
   ... OptionalProperties<ThingProps>;
}

model Thing {
  ... ThingProps;
}

[bterlson]

I should also say, ideally you use visibility for this purpose but that can be a challenge when adapting existing APIs.

[laduke]

Perfect. Thank you for both of those tips.