Laravel external login custom implementation

<?php
/*
custom implementation of users where users login on different site,
however, I do have access to the DB.
Stores user token in session instead of DB.
Not sure if this will work.
*/

//===========================================
//  In CustomUserProvider.php
//===========================================

use Illuminate\Contracts\Auth\UserProvider as IlluminateUserProvider;
use Illuminate\Contracts\Auth\Authenticatable as Authenticatable;

use Illuminate\Support\Facades\DB;


class CustomUserProvider implements IlluminateUserProvider
{
    /**
     * @param  mixed  $identifier
     * @return \Illuminate\Contracts\Auth\Authenticatable|null
     */
    public function retrieveById($identifier)
    {
       // Get and return a user by their unique identifier
         return new CustomUser($identifier);
    }

    /**
     * @param  mixed   $identifier
     * @param  string  $token
     * @return \Illuminate\Contracts\Auth\Authenticatable|null
     */
    public function retrieveByToken($identifier, $token)
    {
       // Get and return a user by their unique identifier and "remember me" token

       if (session('custom_user_token_'.$user->acct_id) == $token)
       {
                return new CustomUser($identifier);
       }

     else
       {
             return null;
       }
    }

    /**
     * @param  \Illuminate\Contracts\Auth\Authenticatable  $user
     * @param  string  $token
     * @return void
     */
    function  updateRememberToken(Authenticatable $user, $token)
    {
        // Save the given "remember me" token for the given user
         session(['custom_user_token_'.$user->acct_id => $token]);
    }

    /**
     * Retrieve a user by the given credentials.
     *
     * @param  array  $credentials
     * @return \Illuminate\Contracts\Auth\Authenticatable|null
     */
    public function retrieveByCredentials(array $credentials)
    {
       // Get and return a user by looking up the given credentials

         // Return null, since user should be logging in using WAYF
       return null;
    }

    /**
     * Validate a user against the given credentials.
     *
     * @param  \Illuminate\Contracts\Auth\Authenticatable  $user
     * @param  array  $credentials
     * @return bool
     */
    public function validateCredentials(Authenticatable $user, array $credentials)
    {
       // Check that given credentials belong to the given user
         // Return false, since user should be logging in using WAYF
         return false;
    }

    public function isDeferred()
    {
      return false;
    }
}

//===========================================
// in CustomUser.php
//===========================================


use Illuminate\Contracts\Auth\Authenticatable;

use Illuminate\Support\Facades\DB;


class CustomUser
    implements Authenticatable
{

    /*
      * Construct with these fields:
      * acct_id
      */

    function __construct($acct_id)
    {
        // user should be created by ciac object, don't have to create new users here

        $results = DB::select("SELECT acct_id, username, email FROM my_user_table WHERE acct_id = :acct_id",[':acct_id' =>$acct_id]);
        $userRow = (array) reset($results);

        if ($userRow == null)
        {
            throw new Exception("Can't find user with id {$acct_id}");
        }

        foreach ($userRow as $property => $value)
        {
            $this->$property = $value;
        }

    }



    /**
     * @return string
     */
    public function getAuthIdentifierName()
    {
        // Return the name of unique identifier for the user (e.g. "id")
         return 'acct_id';
    }

    /**
     * @return mixed
     */
    public function getAuthIdentifier()
    {
        // Return the unique identifier for the user (e.g. their ID, 123)
         return $this->acct_id;
    }

    /**
     * @return string
     */
    public function getAuthPassword()
    {
       // Returns the (hashed) password for the user
         // Laravel doesn't need to know the password (?)
         return null;
    }

    /**
     * @return string
     */
    public function getRememberToken()
    {
       // Return the token used for the "remember me" functionality
         // no need to store in DB, is only relevant for this session
         return session('custom_user_token_obj_'.$this->acct_id);
    }

    /**
     * @param  string  $value
     * @return void
     */
    public function setRememberToken($value)
    {
       // Store a new token user for the "remember me" functionality
         // no need to store in DB, is only relevant for this session
         session(['custom_user_token_obj_'.$this->acct_id => $value]);
    }

    /**
     * @return string
     */
    public function getRememberTokenName()
    {
        // Return the name of the column / attribute used to store the "remember me" token
         return 'token';
    }
}