打字稿泛型未返回正确的类型

Question

we use typescript generics in our project but it seems that when we use them as return type in the base class for example PromiseLike it gets PromiseLike<{}>.

I have created a small app to reproduce the error: https://github.com/ssachtleben/typescript-generics-problem

Can somebody check it if its a mistake in our generics handling or a bug in typescript?

Would be awesome.

Thanks, Sebastian

Answer 1

The compiler isn't able to infer the type in your call to accountService.findOne, so it defaults to 'any'. You'll have to provide it yourself.

 return new AccountService().findOne<Account>({}).then(account => account.username);

You should probably provide a method in your AccountService called findAccount that does this for you, so callers don't have to worry about it.

public findAccount(id: number): PromiseLike<Account> {    
    return this.findOne<Account>({ id: id }); //example
}