Query loop with PHP/Laravel

Okay let's suppose the Database structure is something similar to this

Table: users

int: user_id
int: invited_by

Where invited_by is a foreign key that references user_id in the same table (users).

I have created the following migration to create the above database structure (p.s you are free to create it using raw MySql query)

<?php

use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateUsersTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('users', function (Blueprint $table) {
            $table->increments('user_id');
            $table->integer('invited_by')->unsigned()->nullable();

            $table->foreign('invited_by')
                ->references('user_id')
                ->on('users');
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::drop('users');
    }
}

Then I Inserted into users table some test data as following:

user_id: 1, invited_by: null
user_id: 2, invited_by: 1
user_id: 3, invited_by: 1
user_id: 4, invited_by: 1

Now in User eloquent model I have added those two functions:

/**
 * Function to get the users that were invited by the current user.
 *
 * @return \Illuminate\Database\Eloquent\Relations\HasMany
 */
public function invitees()
{
    return $this->hasMany(User::class, 'invited_by', 'user_id');
}

/**
 * Function to get the user who invited the current user.
 *
 * @return \Illuminate\Database\Eloquent\Relations\BelongsTo
 */
public function invitedBy()
{
    return $this->belongsTo(User::class, 'invited_by', 'user_id');
}

Now let's say if I want to know who invited user of ID 2:

$user = User::where('user_id', 2)->first();
$invitedByUser = $user->invitedBy()->getResults();

If we want to know the users that user of ID 1 invited:

$user = User::where('user_id', 1)->first();
$invitees = $user->invitees()->getResults();

I have tried it and it works as expected. Hope this helps.