exchange-2.0/app/Http/Resources/CurrencyRateResource.php

<?php

namespace App\Http\Resources;

use App\Classes\ValueObjects\Constants\PaymentMethodType;
use Illuminate\Http\Resources\Json\JsonResource;

class CurrencyRateResource extends JsonResource
{
    /**
     * Transform the resource into an array.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return array
     */
    public function toArray($request)
    {
        return [
            'payment_method' => PaymentMethodType::PAYMENT_METHODS_ID[$this->payment_method_type],
            'selling' => [
                'type' => property_exists($this->selling, 'type') ? $this->selling->type : 'rate',
                'value' => property_exists($this->selling, 'value') ? $this->selling->value : $this->selling
            ]
        ];
    }
}