Customizing Model Attribute Serialization with Eloquent Custom Casts

<?php

namespace App\Casts;

use Illuminate\Contracts\Database\Eloquent\CastsAttributes;
use Illuminate\Support\Collection;

// Example Value Object or complex data type
class TagsCollection extends Collection
{
    public function toString(): string
    {
        return $this->implode(',');
    }
}

class AsTagsCollection implements CastsAttributes
{
    public function get($model, string $key, $value, array $attributes)
    {
        return $value ? new TagsCollection(explode(',', $value)) : new TagsCollection();
    }

    public function set($model, string $key, $value, array $attributes)
    {
        if ($value instanceof TagsCollection) {
            return $value->toString();
        }
        if (is_array($value)) {
            return implode(',', $value);
        }
        return $value;
    }
}

// In your Model (e.g., app/Models/Article.php)
namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use App\Casts\AsTagsCollection;

class Article extends Model
{
    protected $casts = [
        'tags' => AsTagsCollection::class,
    ];

    protected $fillable = ['title', 'tags'];
}

// Example Usage:
$article = Article::create([
    'title' => 'My New Article',
    'tags' => ['laravel', 'php', 'eloquent']
]);

// Accessing the cast attribute
$tags = $article->tags; // $tags is an instance of TagsCollection
echo $tags->toString(); // laravel,php,eloquent

// Updating the cast attribute
$article->tags = new TagsCollection(['database', 'orm']);
$article->save();

// Or with an array, which the setter can handle
$article->tags = ['webdev', 'frontend'];
$article->save();