exchange-2.0/app/Models/KeyValuePair.php

<?php

namespace App\Models;
use Illuminate\Database\Eloquent\Relations\MorphTo;
use Illuminate\Database\Eloquent\SoftDeletes;

class KeyValuePair extends AbstractModel
{
    use SoftDeletes;

    protected $table = 'key_value_pairs';

    protected $fillable = [
        'owner_type',
        'owner_id',
        'key',
        'value',
    ];

    /**
     * Get the attributes that should be cast.
     *
     * @return array<string, string>
     */
    protected function casts(): array
    {
        return [
            'deleted_at' => 'datetime',
        ];
    }

    public function owner(): MorphTo
    {
        return $this->morphTo();
    }
}