Undefined Firebase Custom Claims - firebase

Question

I want to add a custom claim to the idtoken on registration here is my cloud function for that:
exports.processSignUp = functions.auth.user().onCreate((newUser) => {
let customClaims = {};
if (newUser.role === "reader") {
customClaims.reader = true
} else if (newUser.role === "writer") {
customClaims.writer = true
}
return admin
.auth()
.setCustomUserClaims(newUser.uid, customClaims)
.then(() => {
return {
message: `success`,
};
});
});
(The newUser object contains a role key that can hold either a string value of writer or reader)
whenever I create a new user the cloud function runs with status ok but later on when I receive the decoded id token there aren't any claims in it so I assume it was null to begin with. I have no idea where my mistake is and couldn't find any documentation that could explain it. Would very much appreciate any help :))

Answer 1

The newUser parameter in the function is of type auth.UserRecord which does not have any custom properties. It only has these properties.
It seems to me that you want to add role - either writer or reader - to a newly created user. Using a custom callable cloud function rather than authentication trigger would be better to avoid race conditions involved in other workarounds.
exports.createNewUser = functions.https.onCall((data, context) => {
const userEmail = data.email;
const userPassword = data.password
const role = data.role
if (!["reader", "writer"].includes(role)) {
return {error: "Invalid Role"}
}
return admin.auth().createUser({ email: userEmail, password: userPassword }).then((newUser) => {
return admin.auth().setCustomUserClaims(newUser.uid, {role: role}).then(() => {
return {data: "New user created successfully"}
})
})
});
This will create a new user with role you need. To call this function from your app, follow this code on the client:
const createNewUser = firebase.functions().httpsCallable('createNewUser');
createNewUser({ email: "userEmail", password: "userPassword", role: "userRole" })
.then((result) => {
// Read result of the Cloud Function.
const response = result.data.data;
});
Please let me know if you need more clarification.