预期返回箭头中的值 function 警告

Question

this pice of code finds a user by id and if is user is not found it creates one but...

I´m getting the "Expected to return a value in arrow function array-callback-return" warning

findUser(id)
    .then((user) => {
        if (user.empty) {
            return createUser()
                .then((user) => setUser(user));
        } else {
            const updatedUser = user.docs[0];
            return {
                id: updatedUser.id,
                ...updatedUser.data(),
            };
        }
    })

I can´t get rid of it and I´m not sure why is happening. thanks. hope this piece of code helps you don´t want to see it all: is a mess :)

Answer 1

The problem is that you're not consistently returning a value from inside findUser 's .then . You should return the createUser call:

if (user.empty) {
  return createUser()
    .then

This is useful because it means that the resulting Promise chain will resolve when createUser and setUser finish. Otherwise, the createUser / setUser Promise will be disconnected from the outside - you won't be able to determine when it finishes, or handle its errors.

Note that you don't need an anonymous callback which calls setUser - you can pass the setUser function itself to the .then :

return createUser()
  .then(setUser);

You also might consider using async / await , the control flow will be clearer:

const user = await findUser(id);
if (user.empty) {
  const createdUser = await createUser();
  // no need to await below if setUser doesn't return a Promise
  await setUser(user);
} else {
  const updatedUser = user.docs[0];
  return {
    id: updatedUser.id,
    ...updatedUser.data(),
  };
}