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 $dates = ['deleted_at'];

    protected $table = 'key_value_pairs';

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

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