Is it possible to "Pick" a subset of properties into a model?

[Elliot Shepherd (elliots)]

The usecase is that we have models that are used by different apis, sometimes with only a subset of the properties. For example, emitting CustomerCreated events to a webhook that only include id, name, email from Customer.

I could create BaseCustomer and have multiple things extend it, but maybe there's another way?

e.g.

model Widget {
  @key id: string;
  weight: int32;
  color: "red" | "blue";
}

model WidgetNoColor extends Pick<Widget, "id" | "weight"> {
}

model WidgetNoWeight extends Widget {
  weight: never;
}

model WidgetCreatedEvent {
  widgetId: Widget["id"]
}

[Brian Terlson (bterlson)]

We don't have Pick yet unfortunately. We have Omit, though it's done with a mutating decorator which is questionably good. That said, you could look at how that works and implement something similar for Omit. Alternatively, you can pull out e.g. id and weight into a separate model and spread it in where needed.

[Elliot Shepherd (elliots)]

I'll check out Omit (which might actually work for some uses) and see how a Pick might operate. But splitting out and using as needed is probably most sensible. Thankyou!

[Bobby Tiernay (btiernay)]

Was there any consideration given to supporting both Omit and Pick as first class utility types?

[Timothee Guerin (timotheeguerin)]

do you mean without the decorator patch, as a more built-in type? If so I think it would be nice but for now those types do make it work well without a design on how those special types would work/new conditional syntax like TypeScript.

[Bobby Tiernay (btiernay)]

without a design on how those special types would work/new conditional syntax like TypeScript
Can you please clarify what you mean regarding "conditional syntax"?

The intuition for my question is that Omit, Pick and others are very frequently used type operations and would probably benefit from first class support in ASTs, etc. I was curious if these were ever considered.

[Elliot Shepherd (elliots)]

The Pick PR was accepted and released in 0.57 - #3488