Flutter get User Data from Firebase - firebase

I want to get User Data from firebase, I need the diplayName of a User. is there any way to get the displayName of a other user with his uid?

There is no way to look up information about another user in Firebase Authentication by using the client-side SDKs of Firebase, as that would be a security risk.
There are two common ways to allow searching the users in a secure way:
Write information about each user to a database (such as Cloud Firestore or the Realtime Database) when they register, and then search the database when needed. That way your code controls what data gets written and thus is searchable.
Firebase has Admin SDKs that run in trusted environments, such as your development machine, a server you control, or Cloud Functions. These SDKs have options to list users, which means you can search them. If you wrap one of the Admin SDKs in a custom API that you build and secure yourself, you can then call that from your Flutter code.
Also see:
React native firebase authentication searching

You can't get the name, or any other details of a user that is not currently signed in using FirebaseAuth.
Instead, you must create a node in your database where you store the name, and any other necessary details by querying the database.

Related

getting user id from phone number in flutter

in the app, which logs the user in only through phone authentication.
now the question is can I get the user id from his phone number(not the user id of the current user though).
I have the access to other users phone number in the app, and I want to get their id for further use.
is it possible in flutter with firebase at the backend?
Looking up the UID for a user based on either phone number or email address is considered a sensitive operation. For this reason such operations are only available in the Admin SDKs, which are designed to be used in trusted environments, such as your development machine, a server you control, or Cloud Functions. For more on these, see the bottom two code samples in looking up user data in the documentation.
If you want to perform such operations from your client-side code, your two main options are:
Store the required mapping in a cloud-hosted database, such Firebase's Realtime Database or Firestore, as Huthaifa also answered.
Create your own custom API on a server or Cloud Functions where you lookup the user through the Admin SDK. Your client-side application code can then call this custom API.
In both of these cases you are in full control of what data you share, and how you secure access.
Sure you can, there are multiple approaches for this, if you post your structure for the user model, or how you are storing them in firebase.
You can run a simple Firebase query like this example:
FirebaseFirestore.instance.collection('users').where('phoneNumber', isEqualTo: thePhonenumberOftheuserYouwant2GetUIDfor).get()
You can also store the available\accessible contacts for every user in their user document, and when your user logs in, it'll fetch all their allowed user numbers.
The more information you provide to your problem, the more StackOverflow can provide you back.

Flutter - Understanding Firebase Admin and how to get a user's information from email/uid/name

I'm making a little Snapchat clone, and a part of this app I'm trying to build is the ability to add a friend and start a conversation with them. I'm using Firebase to manage my users and I'm a little stuck now trying to figure out what works and why I'm getting problems trying to use some methods or functions.
What I want is this simple line of code to work:
var userByEmail = await _admin.app().auth().getUserByEmail("b#gmail.com");
print(userByEmail.toString());
However this has been giving my some problems, most recently, the following error message:
Unhandled Exception: FirebaseAuthError(auth/invalid-credential): Must initialize app with a cert credential or set your Firebase project ID as the GOOGLE_CLOUD_PROJECT environment variable to call verifyIdToken().
Getting to this point made me want to first ask a question about FirebaseAdmin and Auth before continuing and potentially screwing up my app settings.
Is there a simple way to do what I'm trying to do?
I have a Firebase.instance.initializeApp() in my Main function, do I only ever call that once or should I start initilizeApp in the initState of each Stateful Widget where needed?
What does this error message actually mean?
You are trying to use the Firebase Admin SDK in your Flutter code, which is not possible. The Admin SDKs give full administrative access to your Firebase project, which would be a serious security concern if you allow that in your Flutter app.
If you want to allow certain administrative functionality in your application, you will have to make that functionality available yourself. For example, to look up a user by their email address, there are two common approaches:
Store the minimal information about each user in a cloud-accessible database (such as Firebase's Realtime Database or Cloud Firestore) when each user registers with your app, and then look it up from there.
Wrap the getUserByEmail from the Admin SDK in a custom API that you make for yourself, on a server you control or in Cloud Functions. In that API you validate that the user making the call is authorized to do so, then call Firebase through the API you were trying to use, and return the minimal result back to the caller.
Both of these are feasible and can work to solve a variety of use-cases. But if you've never built backend code before, you might find the first approach easier to get started with.
Also see:
How to get Firebase UID knowing email user?
Flutter get User Data from Firebase
The right way to do what you want is using Firebase auth, authenticating your user and using a collection to store and retrieve users information. That auth information provided by firebase should only be used for authentication and security purposes.
The Firebase admin must have a user logged in to work properly, but its purpose is to provide a more administration environment and should not be used inside a clients app, unless its an admin app.
With all that said, lets go for the rescue:
Authenticate your user (using firebase auth);
After auth, save all the user information you want to share with other user inside its own collection (you will need to create one);
When an authenticated user (this is important) 'request any other users data, you query for the data in the previous created collection.

Query for uid with email or name with flutter firebase

So my current flutter project has all users logged in with only google accounts.
Is there a way to query for user UIDs with the user's gmail or google username?
Another followup question:
I can't seem to find a clear documentation for firebase for flutter specifically, is there something like this out there?
There is no way to query across the users in Firebase Authentication from the client-side SDKs, as that would be a security risk.
If you want to allow users to find other users, the two most common approaches are:
Store information about each user in the database (typically either Realtime Database or Cloud Firestore), and search across that.
Wrap the relevant parts of the Admin SDK in a Cloud Function, and call that from your app.
While the second may sound simpler/more common at first, using a database is actually by far more common with Firebase and allows more flexibility for relatively low complexity.

How can one fetch the authorized users along with their details in Firebase

I have a Firebase project, which I'm currently using with android. I need to programmatically fetch details of the users authorized along with the UID, Email, etc. Exactly the way it is shown in firebase (with the search), this web portal will be given to the vendor or the person using it to verify the user's authenticity.
I've attached the screenshot from Firebase, I'm hoping to replicate it the same way with the search. If this is possible, how do I go about doing this?
It's not possible to list users from an Android app, using only the Firebase Authentication SDK. You can list users using the Firebase Admin SDK, but that can only be run on a backend you control, using service account credentials for your project.
It might be easier if you store user info in a database, to be queried by client code, rather than try to have your app try to access auth data directly.

Best practice Fetch user's information from the Firebase User UID

I have integrated Firebase's Facebook and Email Login into my iOS application.
Although, I would like to only store the Firebase User ID in my API database.
Therefore from my backend server (say Ruby) how can I query firebase to get say the user's name and user's email address given that I have their Firebase User UID.
Thanks
To directly read user data for arbitrary users of your app, you'd use the Firebase Admin SDK: https://firebase.google.com/docs/admin/setup. This specific page shows how to read user data: https://firebase.google.com/docs/auth/admin/manage-users#retrieve_user_data
Reading user data through the Admin SDK is currently only available for Node.js and Java. Since Ruby isn't on this list, you'll need to keep the user information elsewhere. The Firebase Database is a common place to store such data, so that any platform can access it through its REST API.

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