用typescript中的属性值更改接口中的属性类型

Question

我有这个接口用于在redux工具包中创建切片

interface AuthState {
authenticated: boolean;
role: number;
currentUser: IUser | null;
isAuthenticating: boolean;
}

如果authenticated为真，有没有办法使currentUser始终为IUser？

因此，当访问currentUser时，我不必检查possibly null。我是ts的新手

Answer 1

您可以使用一个可区分的并集，在authenticated上进行区分，然后与公共属性相交：

type AuthStateUnion = {
authenticated: true;
currentUser: IUser;
} | {
authenticated: false;
currentUser: null;
}
type AuthState = AuthStateUnion & {
role: number;
isAuthenticating: boolean;
}
let state: AuthState = Math.random() > 0.5 ? {
authenticated: true,
currentUser : { name: ""},
role: 1,
isAuthenticating: false
} :{
authenticated: false,
currentUser : null,
role: 1,
isAuthenticating: false
} 
if (state.authenticated) {
state.currentUser.name
} else {
state.currentUser // null
}

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