Data from function is of type unknown - functions v9

Question

I have a cloud function that takes an email and returns the user info, including the uid.

The function is declared like this:

const getUserByEmail = httpsCallable(functions, 'getUserByEmail')
const user = await getUserByEmail({
    email: email,
})

But when I try to read "user.data.id" typescript yells at me because:

"Object is of type 'unknown'.ts(2571) (property)

HttpsCallableResult.data: unknown Data returned from callable function.

What am I missing?

edit: of course I tried "user: any" and TS is happy, but it's not a great solution.

Answer 1

httpsCallable needs type info.

httpsCallable<RequestData, ResponseData>

const getUserByEmail = httpsCallable<{email: string}, {
  user: {
    data: {
      id: string,
    }
  }
}>(functions, 'getUserByEmail');

const { data } = await getUserByEmail({
    email: email,
});

const userId = data.user.data.id;

Answer 2

TS doesn't know what user is. You would have to implement a user type guard.

check out example from docs how TS understands types in each if branch:

function f(x: unknown) {
  if (typeof x === "string" || typeof x === "number") {
    x; // string | number
  }
  if (x instanceof Error) {
    x; // Error
  }
  if (isFunction(x)) {
    x; // Function
  }
}

For your problem something like:

export const isUser(x: any): x is User {
  //here you have to check out props so you are sure x is user
}

for more info check out https://www.typescriptlang.org/docs/handbook/advanced-types.html#user-defined-type-guards