Is there a better approach to this code? ```// cre...

# arrow

[jean]

Is there a better approach to this code?

// create a hash from clear password
return hashPassword(password, pbkdf2Values)
     // search for email/hash pair in db
    .flatMap { database.findUserByCredentials(email, it) }
    .map {
        // if user is registered, check for existing auth token 
        when (val existingToken = database.token(it, userAgent)) {   
            is Either.Left -> createToken(jwtValues, it, userAgent) // no token -> create a new one
            is Either.Right -> existingToken.value // token exists -> return it
        }
    }

I tried to use either.eager{} or fold(ifLeft, ifRight) but I didn’t find any solution more convincing 😕

[simon.vergauwen]

Code style is always a bit subjective but I always prefer either blocks.

either.eager {
  val cred = hashPassword(password, pbkdf2Values).bind()
  val user = database.findUserByCredentials(email, cred).bind()
  database.token(user, userAgent)
   .handleError { createToken(jwtValues, user, userAgent) }
   .bind()
}

[simon.vergauwen]

You can compose`handleError` with database.token to provide a fallback function before you bind the value.

[simon.vergauwen]

Or handleErrorWith if createToken returns another Either.

[jean]

I was not aware of handleError and indeed that make the either block a bit better. Thanks 🙂

[Srki Rakic]

Oh this is nice, I wasn't aware of it also.