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Let's build a super simple referral system with Laravel

Simi Oluwatomi
Back-end developer who loves building data-driven web applications with a focus on usability, reliability, and maintainability.
・6 min read

Sometime ago, I was asked to build a referral system as part of the feature set of a Laravel web application. Referral systems were not new to me but it was my first time building one. Referral systems are used to encourage users of an application to invite other users and get rewarded when people register for that application using their referral link.

I really wanted to keep things super simple but most of what I read online about referral systems were either too complicated or complex for my use case. After some tinkering around, I came up with something so simple I’m surprised it works. Together, we are going to build a referral system and examine some decisions and trade-offs we will have to make along the way.

To start, create a new Laravel project. I’ll name mine simple-referral. Allow composer or the laravel installer do its magic and you should have a barebones Laravel application at your fingertips. Configure the application database, run php artisan make:auth and let’s get cracking.

A referral flow looks something like this

  1. A user clicks a link that takes them to the application register page.
  2. When they register, their registration should be linked to the user whose referral link they used in registering.
  3. The user whose referral link was used to register should get notified that someone registered using their referral link.
  4. The new user should have his or her own referral link.

We could use this scenario to model our eloquent relationships which would look like the following

  • A user can be referred by another user.
  • A user can refer many users.

In essence, we have a One-To-Many relationship. Open the create_users_table migration and make the change below.

$table->unsignedBigInteger('referrer_id');

But wait! Not all users will have a referrer, so let’s make the referrer column nullable. While at it, let's also add a foreign_key constraint to the users table. create_users_table migration should now look like this.

    $table->bigIncrements('id');
    $table->unsignedBigInteger('referrer_id')->nullable();
    $table->foreign('referrer_id')->references('id')->on('users');
    $table->string('name');    
    $table->string('email')->unique();            
    $table->string('password');
    $table->rememberToken();
    $table->timestamps();   

Migrate the database and make the changes below in User.php. In case you didn’t know, you just set up a self-referencing table.


/**
 * The attributes that are mass assignable.
 *
 * @var array
 */
protected $fillable = [
    'referrer_id', 'name', 'email', 'password',
];

/**
 * A user has a referrer.
 *
 * @return \Illuminate\Database\Eloquent\Relations\BelongsTo
 */
public function referrer()
{
    return $this->belongsTo(User::class, 'referrer_id', 'id');
}

/**
 * A user has many referrals.
 *
 * @return \Illuminate\Database\Eloquent\Relations\HasMany
 */
public function referrals()
{
    return $this->hasMany(User::class, 'referrer_id', 'id');
}

Now let's think about referral links and how we want our referral links to look like.

For the application I was building, one of the business requirements was that users have a referral link that could be easily remembered. Over time, I have learned that URLs that can be remembered easily are always short. There are exceptions to this but as I said, they are exceptions. After some back and forth, we agreed that referral links should look like this https://simple-referral/register?ref=username. This would require users to have a unique, unchanging username.

To satisfy this business requirement, amend create_users_table migration like so

//...
$table->string('username')->unique();

Then open User.php and make the following changes

protected $fillable = [
    // ...
    'username',
];

/**
 * The accessors to append to the model's array form.
 *
 * @var array
 */
protected $appends = ['referral_link'];

/**
 * Get the user's referral link.
 *
 * @return string
 */
public function getReferralLinkAttribute()
{
    return $this->referral_link = route('register', ['ref' => $this->username]);
}

Rather than storing the user's referral link in the database, we are using an accessor to compute it. Then we append the attribute to the User model's array or JSON form. To read more about accessors and eloquent serialization, click here and here.

Your requirements for a referral link might be different and here is another option you can consider https://simple-referral/register?ref=referral_token. In this case, edit create_users_table migration like so

 //...
 $table->string('referral_token')->unique();

Then open User.php and

  • Add referral_token to the fillable fields.
  • Append referral_link to the model's array or JSON form.
  • Compute the referral link attribute using the user's referral_token instead of the username.

This method would allow users to have editable usernames but you would have to think of how to generate unique referral tokens for your users. I'll leave you to figure that out.

The User model has been prepped, and the database structure supports our referral system; let's move on to our Controller!

Open App\Http\Controllers\Auth\RegisterController.php. The Controller uses Illuminate\Foundation\Auth\RegistersUsers trait to perform most of it's functions meaning we can override the methods of the trait in the Controller.

/**
 * Show the application registration form.
 *
 * @return \Illuminate\Http\Response
 */
public function showRegistrationForm(Request $request)
{
    if ($request->has('ref')) {
        session(['referrer' => $request->query('ref')]);
    }

    return view('auth.register');
}

/**
 * Get a validator for an incoming registration request.
 *
 * @param  array  $data
 * @return \Illuminate\Contracts\Validation\Validator
 */
protected function validator(array $data)
{
    return Validator::make($data, [
        'name' => ['required', 'string', 'max:255'],
        'username' => ['required', 'string', 'unique:users', 'alpha_dash', 'min:3', 'max:30'],
        'email' => ['required', 'string', 'email', 'max:255', 'unique:users'],
        'password' => ['required', 'string', 'min:8', 'confirmed'],
    ]);
}

/**
 * Create a new user instance after a valid registration.
 *
 * @param array $data
 *
 * @return \App\Models\User
 */
protected function create(array $data)
{
    $referrer = User::whereUsername(session()->pull('referrer'))->first();

    return User::create([
        'name'        => $data['name'],
        'username'    => $data['username'],
        'email'       => $data['email'],
        'referrer_id' => $referrer ? $referrer->id : null,
        'password'    => Hash::make($data['password']),
    ]);
}

It looks like a lot but we are only doing three things

  • Set a session variable named 'referrer' if the register route contains a ref query parameter.
  • Form field validation before creating the user.
  • Retrieve the referrer from the session when creating a user then set its id as the referrer_id of the user being created.

To complete our simple referral system, users should get a notification when new users register using their referral link. To be as flexible and powerful as possible, I'll be using a Notification instead of a Mailable. Run php artisan make:notification nameOfTheNotification to generate a Notification. I'll be naming mine ReferralBonus. I'll leave you to decide the channel(s) through which the notification will be sent.

Open RegisterController.php and override the registered method like so

/**
 * The user has been registered.
 *
 * @param  \Illuminate\Http\Request  $request
 * @param  mixed  $user
 * @return mixed
 */
protected function registered(Request $request, $user)
{
    if ($user->referrer !== null) {
        Notification::send($user->referrer, new ReferrerBonus($user));
    }

    return redirect($this->redirectPath());
}

Here we send a notification to the newly registered user if it has a referrer. We then redirect to the redirect path defined on the RegisterController. Note: Do not forget to import all necessary classes.

Now let's deal with out front-end. Open register.blade.php and add a form input field for username.

//...
<div class="form-group row">
    <label for="name" class="col-md-4 col-form-label text-md-right">{{ __('Username') }}</label>

    <div class="col-md-6">
        <input id="username" type="text" class="form-control @error('name') is-invalid @enderror" name="username" value="{{ old('username') }}" required autocomplete="username">

        @error('username')
            <span class="invalid-feedback" role="alert">
                <strong>{{ $message }}</strong>
            </span>
        @enderror
    </div>
</div>

Now, let's modify home.blade.php to display some user information

<div class="card-body">
    @if (session('status'))
        <div class="alert alert-success" role="alert">
            {{ session('status') }}
        </div>
    @endif

    You are logged in!

    <ul class="list-group mt-3">
        <li class="list-group-item">Username: {{ Auth::user()->username }}</li>
        <li class="list-group-item">Email: {{ Auth::user()->email }}</li>
        <li class="list-group-item">Referral link: {{ Auth::user()->referral_link }}</li>
        <li class="list-group-item">Referrer: {{ Auth::user()->referrer->name ?? 'Not Specified' }}</li>
        <li class="list-group-item">Refferal count: {{ count(Auth::user()->referrals)  ?? '0' }}</li>
    </ul>
</div>

Our simple referral system is now complete. In case you are having challenges following along, you can browse through the repository I created for this tutorial on Github

GitHub logo simioluwatomi / simple-referral

A super simple referral system built with Laravel

Image of User Details

This project demos a super simple referral system built with Laravel. To read the tutorial I wrote for this, click here .

To run the project

  • Clone it to your computer.
  • Run composer install to install application dependencies.
  • Copy .env.example to .env.
  • Run php artisan key:generate to generate an application key.
  • Add database credentials to .env.
  • Run php artisan migrate to migrate the database.
  • To run the tests included, add database credentials for the testing database connection defined in config/database.php to .env.

Discussion (22)

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clementn profile image
Clement

Very nice and very useful. Thank you.
I use it with a small change.

I moved the code to write the referrer into the session

    if ($request->has('ref')) {
        session(['referrer' => $request->query('ref')]);
    }
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from app/Http/Controllers/Auth/RegisterController.php to a custom made middleware app/Http/Middleware/CheckReferrer.php

That way, the ?ref=referrer can be used on any link on the website and not only on register?ref=referrer

P.S. The custom middleware can be created using the artisan command:
php artisan make:middleware CheckAge
then it has to be registered within app/Http/Kernel.php

    protected $middlewareGroups = [
        'web' => [
...........
            \App\Http\Middleware\CheckReferrer::class,
        ],
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jcarlosr profile image
Juan Ramos

Nice suggestion Clement. Although I think the session won't last much and it can be replaced if the user visits a page with a new ref parameter.
I need to keep the referrer value for at least 7 days and set the value only if it's not already there. For this particular case I think I will be using Cookies.

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simioluwatomi profile image
Simi Oluwatomi Author

This is great. I really didn't think about this use case as mine was only focused on registration

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cyprian_dev profile image
Cyprian

So for those who would be using Laravel 8 with jetstream, this stack uses Fortify for authentication and i quote from laravel documentation 'Fortify does not provide its own user interface, it is meant to be paired with your own user interface which makes requests to the routes it registers'. if that is hard to understand then follow the laravel.com/docs/8.x/fortify#intro... for clarity or drop a comment below.

So let's get to the chase. The most important thing in this system is the session that Mr Simi set to cache a session variable named 'referrer' if the register route contains a ref query parameter. now go to App\Providers\FortiftyServiceProvider in the boot() method and paste the code below

Fortify::registerView(function(Request $request) {
if ($request->has('ref')) {
session(['referrer' => $request->query('ref')]);
}
return view('auth.register');
});
Now the code is doing the same as that in the registerController.

Secondly, after caching the ref=user and getting the user's id, you would need to pass in this data in the create() method. You will find this file in the App\Actions\Foritfy\CreateNewUser class. Like what i did, i replaced the codes in this file with that of the RegisterController and then pass in the

    $referrer = User::whereUsername(session()->pull('referrer'))->first();
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This is the code that pulls the referrer's credentials and parses it in to create a new user. Every other thing stays the same from the User class and from the migration class file too.

It worked for me because i was using laravel 8 for a referral system project. Like i said, drop a comment if you have any challanges below...Cheers

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simioluwatomi profile image
Simi Oluwatomi Author

Thanks! I should update this tutorial to reflect the changes in Laravel since it was written but I'm currently swamped with work.

Thanks once again

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dotcorps profile image
dotcorps

where to write Notification code

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simioluwatomi profile image
Simi Oluwatomi Author

You have to create a notification. Kindly refer to the notification section of the Laravel docs to get started with that

laravel.com/docs/8.x/notifications

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devsahm profile image
Fagbenro Damilare Samuel

You just saved me today. I almost wasted the whole day looking for solutions online. The logic is so simple and readable. It worked perfectly.

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simioluwatomi profile image
Simi Oluwatomi Author

I used to overthink things like this and think of very complex solutions that cover a lot of edge cases. But then I realized that if the solution to something is becoming too complex, maybe, just maybe I'm overthinking it. That has really helped me a lot

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hendisantika profile image
Hendi Santika

Very good article. Simple & good explanation. You just saved me today. The logic is so simple and readable. It worked perfectly.

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christopherokonkwo profile image
Christopher C. Okonkwo

You really made it simple. Of all its clean without external packages. Kudos Bro

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simioluwatomi profile image
Simi Oluwatomi Author

thank you. that was the aim from the get go

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sirg97 profile image
SirG

Thanks for this!

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developia profile image
Opiaaustin

works fine for me just have an issue with, after using a referral link to register i get the error cant find call referralbonus, and i have imported the class, any ideas?

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fathra profile image
FathRa

Can we use it on Laravel 8 with Laravel Breeze?

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fathra profile image
FathRa

Can anyone help me? why 'referrer_id' is null when i registered another user with 'referral_link' ?

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cyprian_dev profile image
Cyprian

the session may not be set properly

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equimper profile image
Emanuel Quimper

Nice job. Really clean and well explain. Thank you :)

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simioluwatomi profile image
Simi Oluwatomi Author

Thank you! Glad that you found it super helpful

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smarthech profile image
ebuka john

This is really easy to comprehend. the best referral tutorial i have seen online. please i would appreciate if you can make a tutorial on multi-level referral system thank you

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simioluwatomi profile image
Simi Oluwatomi Author

At this point, I must ask what a multi-level referral system is. Maybe, just maybe I might be able to come up with something

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jhapali9 profile image
bhola9

I really appreciate your super simple referral system.... Now I can make my own referral system with your idea ... Thanks a lot !!!