Only use "prop" with primitive values and never with object values

[sisp]

The documentation of props states:

https://github.com/xaviergonz/mobx-keystone/blob/1f375e5520b2aae291ca6e99f4e1ecbbc44d498c/packages/lib/src/model/prop.ts#L63-L64

But in the "Flows (async actions)" section of the docs, the book store example has a prop<Book[]>(() => []) prop:

@model("myApp/Auth")
class BookStore extends Model({
  books: prop<Book[]>(() => []),
}) {
  // ...
}

Are non-primitive types in prop in fact allowed and if not, how should a non-primitive prop be declared, e.g. a nested object prop for which I don't want to define a separate class/model?

[xaviergonz]

The "this" in the docs refers to the non lambda initializer. This is, primitives can be initialized with or without lambdas, but non primitives have to use the lambda always. (guess I should make the docs more clear)

[sisp]

Ah, now that you're saying it like this, I double-checked and it is stated in the docs - I didn't read it properly.

Without runtime type checking:

• prop<T>() - A property of a given type, with no default set if it is undefined in the initial data.
• prop<T>(defaultValue: T) - A property of a given type, with a default set if it is undefined in the initial data. Use this only for default primitives.
• prop<T>(defaultFn: () => T) - A property of a given type, with a default value generator if it is undefined in the initial data. Usually used for default objects / arrays / models.

Sorry, my fault.