Hook typing and find method parsing issue #2147
Description
I use the Hook type when declaring my hook:
type PushToken = {
token: string;
applicationSlug: string;
createdAt?: Date;
}
const handleCreate: Hook<PushToken> = ({ data, service, result }) => {
if (!data) {
return;
}
const { token, applicationSlug } = data;
return service
.find({ query: { token }, paginate: false })
.then((tokens) => tokens.length)
;
}Works fine, except for the last then callback.
The tokens.length throw the following typescript error:
Property 'length' does not exist on type 'PushToken | PushToken[] | Paginated<PushToken>'.
Property 'length' does not exist on type 'PushToken'.ts(2339)
This is caused by the following signature:
find (params?: Params): Promise<T | T[] | Paginated<T>>;
I may have only one instance but also an array or a Paginated instance.
So I tried to force the typing like this:
.then((tokens: PushToken[]) => tokens.length)But then give me now an error on the function typing itself:
Argument of type '(tokens: PushToken[]) => number' is not assignable to parameter of type '(value: PushToken | PushToken[] | Paginated<PushToken>) => number | PromiseLike<number>'.
Types of parameters 'tokens' and 'value' are incompatible.
Type 'PushToken | PushToken[] | Paginated<PushToken>' is not assignable to type 'PushToken[]'.
Type 'PushToken' is missing the following properties from type 'PushToken[]': length, pop, push, concat, and 26 more.ts(2345)
The only way I have to get rid of this error is to set the any type to my tokens params, but I loose all the interest of typescript then.
Not sure if it's a bug, but I can't find any reliable example for that on the documentation.