bike-api/app/Models/Model.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model as BaseModel;

class Model extends BaseModel
{
    protected $guarded = [];

    public function scopeMerchant($query, $merchant_id = false)
    {
        if (!$merchant_id) {
            $merchant_id = merchant_id();
        }
        return $query->where('merchant_id', $merchant_id);
    }
}