Firebase authentication with MVVM kotlin

Question

I m new in MVVM and jetpack library. i have an simple application of firebase Authentication , Registration and login. i try many code but i am not getting flow for view Model and repertory. so any one can convert this code with view model and how it works.

Here is code for login

  auth = FirebaseAuth.getInstance()

  fun login(view: View){
        var email:String = binding.editTxtEmail.text.toString()
        var password:String = binding.editTxtPassword.text.toString()

        auth.signInWithEmailAndPassword(email,password).addOnCompleteListener { task ->
                if(task.isSuccessful){
                    val intent= Intent(this,MainActivity::class.java)
                    startActivity(intent)
                    finish()
                }
            }.addOnFailureListener { exception ->
                Toast.makeText(applicationContext,exception.localizedMessage, Toast.LENGTH_LONG).show()
            }
        }

Answer 1

First, you need to add a ViewModel and then add two methods in the ViewModel that accept email and passwords like this.

class AuthViewModel: ViewModel() {

fun handleSignIn(email: String, password: String) {

}

fun handleSignUp(email: String, password: String, confirmPassword: String) {

}
}

Then you need to add an enum or sealed class to represent the possible states of your login flow, here is an example:

sealed class AuthState {
object Idle : AuthState()
object Loading : AuthState()
object Success : AuthState()
class AuthError(val message: String? = null) : AuthState()
}

Then you need to add an observable state and expose it as LiveData like this:

 private val _authState by lazy { MutableLiveData<AuthState>(AuthState.Idle) }
val authState: LiveData<AuthState> = _authState

With that added you can now update your methods to handle sign and sign up like this:

fun handleSignUp(email: String, password: String, confirmPassword: String) {
    if (!isEmailValid(email)) {
        _authState.value = AuthState.AuthError("Invalid email")
        return
    }
    if (password != confirmPassword) {
        _authState.value = AuthState.AuthError("Password does not match")
        return
    }
    FirebaseAuth.getInstance().createUserWithEmailAndPassword(
        email, password)
        .addOnCompleteListener { task ->
            if (task.isSuccessful) {
                Log.i(TAG,"Email signup is successful")
                _authState.value = AuthState.Success
            } else {
                task.exception?.let {
                    Log.i(TAG,"Email signup failed with error ${it.localizedMessage}")
                    _authState.value = AuthState.AuthError(it.localizedMessage)
                }
            }
        }
}

You can then listen to the list

val authState by viewModel.authState.observeAsState(AuthState.Idle)

Good luck.