I use Flutter and Firebase, just ask myself how to allow users to add items to cart when they're not logged in yet and keep the cart when they logging in, anyone have an idea for this ?
On Firebase you'd typically start the user off with an anonymous authentication account. With that sort of account, Firebase generates a user ID (UID) for the user, without them having to enter any credentials. You then associate the cart/items with the UID, and then when you/they are ready to identify themselves, you can sign them in with another provider, and link that to the anonymous account.
I've provided links to the documentation for Android developers above, but the same functionality is available in the FlutterFire libraries too. For example, anonymous sign-in on Flutter is as simple as:
UserCredential userCredential = await FirebaseAuth.instance.signInAnonymously();
you can store this data in a separate database SQL lite as an example
Related
My app makes the user create a new anonymous ID automatically when downloading the app and when the user logs in, for example, by Facebook, the app change UID.
The problem is when I call FirebaseAuth.instance.signInWithCredential, It creates a new UID or change to UID that links to this credential, and the anonymous ID is never deleted. If many users relogin this app, many unuse anonymous ID and data will be garbage in firebase.
I have an idea to store UID in a variable, and when sign-in is successful, I delete using that UID, but firebase allows delete UID only current account. How can I solve this?
It sounds like you want to allow a user that you signed in anonymously to upgrade to an identified account. The idiomatic way to do that is to link the Facebook account to the existing anonymous account, so that the UID remains the same. To do this, follow the process described in the documentation on account linking and in the FlutterFire documentation on linking user accounts.
I use Flutter and Firebase, just ask myself how to allow users to add items to cart when they're not logged in yet and keep the cart when they logging in, anyone have an idea for this ?
On Firebase you'd typically start the user off with an anonymous authentication account. With that sort of account, Firebase generates a user ID (UID) for the user, without them having to enter any credentials. You then associate the cart/items with the UID, and then when you/they are ready to identify themselves, you can sign them in with another provider, and link that to the anonymous account.
I've provided links to the documentation for Android developers above, but the same functionality is available in the FlutterFire libraries too. For example, anonymous sign-in on Flutter is as simple as:
UserCredential userCredential = await FirebaseAuth.instance.signInAnonymously();
you can store this data in a separate database SQL lite as an example
I want to provide a way that users can change their sign in method in my App using Firebase Auth.
For example, if previously a user signed up using Email and Password, then he/she wants to switch to Facebook or Google Sign in method. Then how do I do this without changing the user's UID ?
Probably something like:
firebase.auth()
.signInWithEmailAndPassword('you#domain.com', 'password')
.then((userCredential) {
userCredential.user.updateSignInMethod(method: facebook)
.then((userData) => loginWithFacebookProcedure());
})
Is it possible? If yes, how to do that ?
Thanks
There is no direct ability to "switch" authentication providers with Firebase Authentication. Once an account signs up with a provider (such as email/password), that option will always be available to the user of that account.
What you can do instead is link additional providers to an existing account, which will allow the user to authenticate using any of the providers linked to that account. Until you unlink them.
So, if you really want to "switch", you will actually have to link to another provider, then unlink the old provider. But that seems like a waste of effort when you can simply retain all of the linked providers for the user to choose from.
I know UID is used because it is unique. But in my app, all of them are registered with Google ID, Google ID is also unique. Should I use UID?
yes it is better to use the uid.
From the docs:
You can let your users authenticate with Firebase using their Google Accounts by integrating Google Sign-In into your app.
So after you authenticate the users, the uid will be in the authentication page in firebase. That id will help you later in the firebase database also and it is easier to use and add in the database.
Can easily be gotten using this:
FirebaseUser user=FirebaseAuth.getInstance().getCurrentUser();
Then you can use the method getUid() to get the userid. So using it will make the work easier for you.
From the docs:
After a user signs in for the first time, a new user account is created and linked to the credentials—that is, the user name and password, phone number, or auth provider information—the user signed in with. This new account is stored as part of your Firebase project, and can be used to identify a user across every app in your project, regardless of how the user signs in.
Also check this link: https://firebase.google.com/docs/auth/android/google-signin (Next Step section)
I'll suggest you use email ID instead of UID because if the user account is deleted from your Firebase Auth (either you delete it using Admin SDK, or perform a manual deletion on console), the next time user signs in with the same email ID will now give you a different UID and therefore all of your data in your database which rely on your UID won't be accessible.
However, you can't use use an email ID as it is, because Firebase key doesn't allow you to use . (dot) as keys, so just replace your . with a ,. You can find more information here.
TL;DR
Use email ID as it will always be unique unlike UID which gets generated every time a user signs in if that ID was previously deleted on Firebase Authentication server.
I have been using Firebase authentication for a while and I have been using Facebook and Google logins. When I started it was not possible (or I didn't know) that you can limit on account per email and took care of it with Firebase database security rules and some code. In the database now I only have one account per email, but in the authentication accounts I have multiples per email. I would like to merge them or after the fact add the one account per email rule. Is that possible? If yes, how? And if not, is there any work around? It would be great to let people merge accounts. Thanks!
It is possible to merge accounts with the same email, even after some accounts have been created in Firebase Authentication.
First step is to disallow multiple-accounts-per-email by changing the setting in your Firebase project console. The change will only be applied to new users - all existing users will still sign into their existing accounts as before.
Since your app only uses Google/Facebook login, you can safely delete unwanted authentication accounts from the Firebase Console. Assuming in your database there is an entry (userid_1, email), and in you authentication project there are two accounts for the email (userid_1, email, Google) and (userid_2, email, Facebook). You can delete the (userid_2, email, Facebook) account using the Firebase Console or Firebase admin SDK. All subsequent logins with the same email, no matter via Google or Facebook, will always return the userid_1 account.