问题
I want to be able to check if an email address is already been used (so if somebody put test1@test.com but another user already registered with that email account).
I have a simple test if it has NOT been used an image view shows a green arrow, if it HAS been used then it is red x
when I create the user I use the following code
FIRAuth.auth()?.createUser(withEmail: email, password: password, completion: { (user, error) in
if error == nil {
self.ref.child("userEmails").child((user?.uid)!).setValue(email)
FIRAuth.auth()!.signIn(withEmail: email,
password: password)
} else {
//registration failure
}
what I am trying to do to check is
func checkIfEmailExists(textField: UITextField) {
let ref = FIRDatabase.database().reference()
let email = firstContainerTextField.text ?? ""
ref.child("userEmails").queryEqual(toValue: email)
.observe(.value, with: { snapshot in
if (self.firstContainerTextField.text?.isEmpty)! {
self.firstContainerImage.image = UIImage.init(named: "emptyBlue.png")
} else if !(self.firstContainerTextField.text?.isEmpty)! && !snapshot.exists() {
self.firstContainerImage.image = UIImage.init(named: "redEx.png")
} else if snapshot.exists() {
self.firstContainerImage.image = UIImage.init(named: "greenCheck.png")
}
});
}
So far it does not work as I can see in my database that test1@test.com exists. Can somebody tell me what I missed?
EDIT
I have updated my code. I am using hasChildren and I searched for similar questions and they seem to point this direction, but I still cannot get the result I am looking for
func checkIfEmailExists(textField: UITextField) {
let ref = FIRDatabase.database().reference()
let email = firstContainerTextField.text ?? ""
ref.child("userEmails").queryEqual(toValue: email)
.observe(.value, with: { snapshot in
if !snapshot.hasChildren() {
self.firstContainerImage.image = UIImage.init(named: "redEx.png")
} else {
for child in snapshot.children.allObjects as! [FIRDataSnapshot] {
let tmp = child.value as! String
if tmp == email {
self.firstContainerImage.image = UIImage.init(named: "greenCheck.png")
}
}
}
});
}
Edit 2
I changed how I set my user up
self.ref.child("users").child((user?.uid)!).setValue(["Email": email])
so now my database looks like this
users
*****uid*****
Email: "test@test.com
回答1:
As I commented earlier: you'll need to check whether the query has any results by calling snapshot.hasChildren().
func checkIfEmailExists(textField: UITextField) {
let ref = FIRDatabase.database().reference()
let email = firstContainerTextField.text ?? ""
ref.child("userEmails").queryEqual(toValue: email)
.observe(.value, with: { snapshot in
if (!snapshot.hasChildren()) {
// User doesn't exist yet...
}
});
}
回答2:
The following is the structure of the Firebase function you might be looking for (Swift 4):
Auth.auth().fetchProviders(forEmail: emailAddress, completion: {
(providers, error) in
if let error = error {
print(error.localizedDescription)
} else if let providers = providers {
print(providers)
}
})
If the email address is already registered to a user, you will get a list of the providers that the email address is used for. Otherwise, the list of providers will be empty, and thus the email address is not registered.
来源：https://stackoverflow.com/questions/41372354/swift-firebase-check-if-email-is-already-in-use