DEV Community

Cover image for How to implement a simple like system with Laravel
Benjamin Delespierre
Benjamin Delespierre

Posted on • Edited on

How to implement a simple like system with Laravel

#laravel #php #tutorial

This tutorial has been updated for Laravel 8 (I also fixed a few issues).

A working implementation of this tutorial is also available on GitHub, enjoy!

In this (short) tutorial, I will show you how to add likes on any Laravel Eloquent Model.

// create something...
$something = new Post(['title' => "Laravel is AWESOME!"]);

// add a like to $something
$user->like($something);

// has $user has liked $something?
$user->hasLiked($something);

// how many likes does $something has?
$something->likes()->count();

// remove a like from $something
$user->unlike($something);
Enter fullscreen mode Exit fullscreen mode

We're going to implement this using traits and interfaces. Models "equipped" with the likeable capabilities will look like this:

class Post extends Model implements Likeable
{
    use Likes;
}
Enter fullscreen mode Exit fullscreen mode

I like to builds things from ground up, so we'll start with the database and we'll climb our way up to the browser. En route, we'll use many components provided by Laravel 8, which makes this tutorial a great exercise for beginners.

This tutorial covers:

  • Migrations
  • Models
  • Contracts (interfaces)
  • Concerns (traits)
  • Controllers
  • Requests
  • Gates
  • Routes
  • Views

I won't bother you with details on how everything works, who got time for that? I believe experience is the only teacher. If you need me to explain something specific, let me know in the comments or come chat with me. That being said, let's dive into it!

1. Migrations

Run

php artisan make:migration create_likes_table --create=likes
Enter fullscreen mode Exit fullscreen mode

In database/migrations/(date)_create_likes_table.php

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

class CreateLikesTable extends Migration
{
    public function up()
    {
        Schema::create('likes', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->foreignId('user_id')->constrained()->onDelete('cascade');
            $table->morphs('likeable');
            $table->timestamps();
        });
    }

    public function down()
    {
        Schema::dropIfExists('likes');
    }
}
Enter fullscreen mode Exit fullscreen mode

2. Model

Run

php artisan make:model Like
Enter fullscreen mode Exit fullscreen mode

In app/Models/Like.php

namespace App\Models;

use App\Models\User;
use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Like extends Model
{
    use HasFactory;

    public function user()
    {
        return $this->belongsTo(User::class)->withDefault();
    }

    public function likeable()
    {
        return $this->morphTo();
    }
}
Enter fullscreen mode Exit fullscreen mode

3. Contract (interface)

In app/Contrats/Likeable.php (you need to create the app/Contracts folder)

namespace App\Contracts;

use Illuminate\Database\Eloquent\Relations\MorphMany;

interface Likeable
{
    public function likes(): MorphMany;
}
Enter fullscreen mode Exit fullscreen mode

4. Concern (trait)

In app/Models/Concerns/Likes.php (you need to create the app/Models/Concerns folder)

namespace App\Models\Concerns;

use App\Models\Like;
use Illuminate\Database\Eloquent\Relations\MorphMany;

trait Likes
{
    public function likes(): MorphMany
    {
        return $this->morphMany(Like::class, 'likeable');
    }
}
Enter fullscreen mode Exit fullscreen mode

5. Likeable models

For the sake of the example, I'm going to use a post model generated using php artisan make:model Post. The logic is exactly the same regardless of the models you're using.

In app/Models/Post.php

namespace App\Models;

use App\Contracts\Likeable;
use App\Models\Concerns\Likes;
use Illuminate\Database\Eloquent\Model;

class Post extends Model implements Likeable
{
    use Likes;
}
Enter fullscreen mode Exit fullscreen mode

6. User

In app/Models/User.php add those methods

namespace App\Models;

use App\Contracts\Likeable;
use App\Models\Like;
// other namespaces...

class User extends Authenticatable
{
    // other user stuff...

    public function likes()
    {
        return $this->hasMany(Like::class);
    }

    public function like(Likeable $likeable): self
    {
        if ($this->hasLiked($likeable)) {
            return $this;
        }

        (new Like())
            ->user()->associate($this)
            ->likeable()->associate($likeable)
            ->save();

        return $this;
    }

    public function unlike(Likeable $likeable): self
    {
        if (! $this->hasLiked($likeable)) {
            return $this;
        }

        $likeable->likes()
            ->whereHas('user', fn($q) => $q->whereId($this->id))
            ->delete();

        return $this;
    }

    public function hasLiked(Likeable $likeable): bool
    {
        if (! $likeable->exists) {
            return false;
        }

        return $likeable->likes()
            ->whereHas('user', fn($q) =>  $q->whereId($this->id))
            ->exists();
    }
}
Enter fullscreen mode Exit fullscreen mode

7. Controller

Run

php artisan make:controller LikeController
Enter fullscreen mode Exit fullscreen mode

In app/Http/Controllers/LikeController.php

namespace App\Http\Controllers;

use App\Http\Requests\LikeRequest;
use App\Http\Requests\UnlikeRequest;

class LikeController extends Controller
{
    public function like(LikeRequest $request)
    {
        $request->user()->like($request->likeable());

        if ($request->ajax()) {
            return response()->json([
                'likes' => $request->likeable()->likes()->count(),
            ]);
        }

        return redirect()->back();
    }

    public function unlike(UnlikeRequest $like)
    {
        $request->user()->unlike($request->likeable());

        if ($request->ajax()) {
            return response()->json([
                'likes' => $request->likeable()->likes()->count(),
            ]);
        }

        return redirect()->back();
    }
}
Enter fullscreen mode Exit fullscreen mode

8. Requests

Run

php artisan make:request LikeRequest
php artisan make:request UnlikeRequest
Enter fullscreen mode Exit fullscreen mode

In app/Http/Requests/LikeRequest.php

namespace App\Http\Requests;

use App\Contracts\Likeable;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Foundation\Http\FormRequest;

class LikeRequest extends FormRequest
{
    public function authorize()
    {
        return $this->user()->can('like', $this->likeable());
    }

    public function rules()
    {
        return [
            // the class of the liked object
            'likeable_type' => [
                "bail",
                "required",
                "string",
                function ($attribute, $value, $fail) {
                    if (! class_exists($value, true)) {
                        $fail($value . " is not an existing class");
                    }

                    if (! in_array(Model::class, class_parents($value))) {
                        $fail($value . " is not Illuminate\Database\Eloquent\Model");
                    }

                    if (! in_array(Likeable::class, class_implements($value))) {
                        $fail($value . " is not App\Contracts\Likeable");
                    }
                },
            ],

            // the id of the liked object
            'id' => [
                "required",
                function ($attribute, $value, $fail) {
                    $class = $this->input('likeable_type');

                    if (! $class::where('id', $value)->exists()) {
                        $fail($value . " does not exists in database");
                    }
                },
            ],
        ];
    }

    public function likeable(): Likeable
    {
        $class = $this->input('likeable_type');

        return $class::findOrFail($this->input('id'));
    }
}
Enter fullscreen mode Exit fullscreen mode

Fortunately for us, the unlike request is very easy since it's basically the same request with a minor difference in the authorize method.

In app/Http/Requests/UnlikeRequest.php

namespace App\Http\Requests;

use App\Http\Requests\LikeRequest;

class UnlikeRequest extends LikeRequest
{
    public function authorize()
    {
        return $this->user()->can('unlike', $this->likeable());
    }
}
Enter fullscreen mode Exit fullscreen mode

9. Gates

In app/Providers/AuthServiceProvider.php

namespace App\Providers;

use App\Contracts\Likeable;
use App\Models\User;
use Illuminate\Auth\Access\Response;
use Illuminate\Foundation\Support\Providers\AuthServiceProvider as ServiceProvider;
use Illuminate\Support\Facades\Gate;

class AuthServiceProvider extends ServiceProvider
{
    protected $policies = [
        // your policies...
    ];

    public function boot()
    {
        $this->registerPolicies();

        // $user->can('like', $post)
        Gate::define('like', function (User $user, Likeable $likeable) {
            if (! $likeable->exists) {
                return Response::deny("Cannot like an object that doesn't exists");
            }

            if ($user->hasLiked($likeable)) {
                return Response::deny("Cannot like the same thing twice");
            }

            return Response::allow();
        });

        // $user->can('unlike', $post)
        Gate::define('unlike', function (User $user, Likeable $likeable) {
            if (! $likeable->exists) {
                return Response::deny("Cannot unlike an object that doesn't exists");
            }

            if (! $user->hasLiked($likeable)) {
                return Response::deny("Cannot unlike without liking first");
            }

            return Response::allow();
        });
    }
}
Enter fullscreen mode Exit fullscreen mode

10. Routes

In routes/web.php

Route::middleware('auth')->group(function () {
    Route::post('like', 'LikeController@like')->name('like');
    Route::delete('like', 'LikeController@unlike')->name('unlike');
});
Enter fullscreen mode Exit fullscreen mode

11. Views (Blade)

For the sake of the example, I'm going to use a $post variable representing an App\Models\Post model (as described above). You're obviously free to use whatever model you like, as long as they implement the App\Contracts\Likeable interface and possess the App\Models\Concerns\Likes trait.

In resources/views/like.blade.php:

{{ trans_choice('{0} no like|{1} :count like|[2,*] :count likes', count($model->likes), ['count' => count($model->likes)]) }}

@can('like', $model)
    <form action="{{ route('like') }}" method="POST">
        @csrf
        <input type="hidden" name="likeable_type" value="{{ get_class($model) }}"/>
        <input type="hidden" name="id" value="{{ $model->id }}"/>
        <button>@lang('Like')</button>
    </form>
@endcan

@can('unlike', $model)
    <form action="{{ route('unlike') }}" method="POST">
        @csrf
        @method('DELETE')
        <input type="hidden" name="likeable_type" value="{{ get_class($model) }}"/>
        <input type="hidden" name="id" value="{{ $model->id }}"/>
        <button>@lang('Unlike')</button>
    </form>
@endcan
Enter fullscreen mode Exit fullscreen mode

In resources/views/post.blade.php:

<div class="post">
    <h3>{{ $post->title }}</h3>
    <p>{{ $post->body }}</p>
    @include('like', ['model' => $post])
</div>
Enter fullscreen mode Exit fullscreen mode

Congratulations! You have now finished this tutorial and have implemented a basic, yet robust like system!

Tell me what you think! Especially if you faced difficulties understanding and/or implementing. I always do my best to respond to comments and help my readers.

From the same author:

Latest comments (39)

Collapse
 
imozaiingame profile image
Ozai.hft • • Edited

How the user look what was his liked ? @bdelespierre

Collapse
 
lucasmartins-me profile image
Lucas Martins •

$something->likes

Collapse
 
atr0x23 profile image
atr0x23 •

Hi, I am new to Laravel. I followed your orders here but when i am trying to run and see a view (blade) with the posts from db I am getting this error:

Trait 'App\Concerns\Likes' not found

What am I missing?
Thanks in advance.

Collapse
 
jyrjsinhsolanki profile image
Jayrajsinh Solanki •

Thanks for the tutorial...

Collapse
 
squarou profile image
Benjamin •

Hello @bdelespierre

That's really brillant, thanks a lot for sharing!

I noticed an error in app/Http/Controllers/LikeController.php

Change
public function unlike(UnlikeRequest $like)
with
public function unlike(UnlikeRequest $request) ;-)

Thank you again,

Collapse
 
fatahidzhar profile image
FatahIdzhar •

i get proble on stdClass::$Likes

More details are here :
flareapp.io/share/q5YLj4j7#F62

Collapse
 
zhandos998 profile image
zhandos998 •

using Post::all();
no DB::table('post')->get();

Collapse
 
fatahidzhar profile image
FatahIdzhar • • Edited

i get proble on
Undefined property: stdClass::$likes

flareapp.io/share/q5YLj4j7#F62

Collapse
 
bdelespierre profile image
Benjamin Delespierre •

Your $model variable shouldn't be an stdClass instance. It should be a Post instance. (or anything with the Likes trait).

I suggest you dump this variable with dd($model) in the controller before returning the view and try to understand what's going on.

Good luck!

Collapse
 
fatahidzhar profile image
FatahIdzhar • • Edited

I've tried it, it's still an error in the
Undefined property: stdClass::$likes

and already using dd()

Collapse
 
stleroux profile image
stleroux •

Hello,
I have run into a weird issue.
Wen I run the code on the localhost where I do my development, everything works fine.
This is a Windows 10 machine running PHP 7.4.15

However, when I transfer my files to my Ubuntu 18.04 server, I get the following error message on all pages :
->> syntax error, unexpected '=>' (T_DOUBLE_ARROW), expecting '{' <<-
And it is pointing to


      $likeable->likes()
        ->whereHas('user', function($q) => $q->whereId($this->id))
        ->delete();
Enter fullscreen mode Exit fullscreen mode

in my User model.
I am running PHP 7.4.21 on the server.
If I comment out the lines, the pages load properly.
Hopefully, this is enough info to TS, if not, please let me know what else is needed.
Thanks

Collapse
 
bdelespierre profile image
Benjamin Delespierre •

In the code snippet you provided, there's a typo on the arrow function, it should be:

      $likeable->likes()
        ->whereHas('user', fn($q) => $q->whereId($this->id))
        ->delete();
Enter fullscreen mode Exit fullscreen mode
Collapse
 
stleroux profile image
stleroux •

Hi,
Love the code. Straight forward and works like a charm.
Is there a way to eager load the likes data on index pages?
I tried adding "likes" to the with query but it doesn't seem to reduce the amount of queries being performed.

Thanks

Collapse
 
bdelespierre profile image
Benjamin Delespierre • • Edited

I have just tried

$posts = Post::latest()->with('likes')->take(5)->get();
Enter fullscreen mode Exit fullscreen mode

Using the demo project and Laravel Debug bar.

From 8 queries (with the N+1) problem you mention, I now have only 4 👍

See before and after

Hint: be sure to place the ->with('...') part BEFORE ->get() or ->all().

Collapse
 
stleroux profile image
stleroux •

Actually, I was using the code in the index page and doing a @can ('like') and @can ('unlike') which was querying the DB twice per record. I changed the @can ('unlike') for @else and now the duplicate queries are gone.
Thanks

Thread Thread
 
bdelespierre profile image
Benjamin Delespierre • • Edited

Yes, that's because the gates in AuthServiceProvider are using User::hasLike :

    public function hasLiked(Likeable $likeable): bool
    {
        if (! $likeable->exists) {
            return false;
        }

        return $likeable->likes()
            ->whereHas('user', fn($q) =>  $q->whereId($this->id))
            ->exists();
    }
Enter fullscreen mode Exit fullscreen mode

You may change it to use a cache, like this (actual working solution) :

    public function hasLiked(Likeable $likeable): bool
    {
        if (! $likeable->exists) {
            return false;
        }

        return $this->likes->contains(
            fn($like) => $like->likeable_type == get_class($likeable) && $like->likeable_id == $likeable->id
        );
    }
Enter fullscreen mode Exit fullscreen mode

It should minimize the number of queries. It's ugly but it works!

Result before with 15 queries (one per @can('like')) and after only 6!

Collapse
 
bdelespierre profile image
Benjamin Delespierre •

Can you show us what you tried?

Collapse
 
snalpas profile image
Silvere •

Nice work that will serve as a reference for the design of features on Laravel 8
Thank you 👍

Collapse
 
webfuelcode profile image
webfuelcode • • Edited

I followed the steps, running the localhost says "trait app\concerns\likeable" not found... Tried a lot to figure out the reason but failed. It may be a typo or the new version is the reason. Can you tell me...

Collapse
 
bdelespierre profile image
Benjamin Delespierre •

It's very unlikely a version issue (if you're running PHP7.2+ of course).

If you see the 'not found' error it means a namespace import is missing.

View full discussion (39 comments)