Trait is empty after spawning entity?

[maurice]

Hi,

I am new to koota but it looks interesting for one of my current projects (React + PixiJS + koota + state-machines).

Am I wrong to think that entity.get(Trait) should return effectively the object literal that I provided when spawning the entity?

Eg

import { createWorld, trait } from "koota";

const world = createWorld();

const Car = trait();
const Color = trait<{ readonly color: string }>();

const car = world.spawn(Car, Color({ color: "red" }));

console.log("car has Car", car.has(Car));
console.log("car has Color", car.has(Color));
console.log("car Color", car.get(Color), car.get(Color)?.color);

The output is

car has Car true
car has Color true
car Color {} undefined

I am expecting the last line of output to be car Color { color: 'red' } red.

Please help me understand what I'm doing wrong!

Thanks

[maurice]

Update: I found that providing a default value for the data trait fixes this

const Color = trait<{ readonly color: string }>({ color: "yellow" });

Now in the output I do see

car has Car true
car has Color true
car Color {
  color: "red",
} red

If it is indeed mandatory to have a default value for the trait perhaps the TypeScript types could be improved to flag this an an error?

[krispya]

Hi Maurice. Yes, a schema is required for the trait. I'll check to see why it doesn't give an error if you explicitly type the trait but don't pass in a matching schema. This should be fixable.

By the way, if no schema is passed in then the trait is considered a tag and holds no data. This is why you are seeing undefined.

[maurice]

Great thanks for confirming 😊 I'll probably start omitting the generic unless the inferred type isn't good enough 😄

[krispya]

This PR should fix the issue you found: #84