Return object with row no in database

RowNoScope.php

<?php

namespace App\Scopes;

use Illuminate\Database\Eloquent\Scope;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Support\Facades\DB;

class RowNoScope implements Scope
{
    /**
     * Apply the scope to a given Eloquent query builder.
     *
     * @param  \Illuminate\Database\Eloquent\Builder  $builder
     * @param  \Illuminate\Database\Eloquent\Model  $model
     * @return void
     */
    public function apply(Builder $builder, Model $model)
    {
        if(is_null($builder->getQuery()->columns)){
            $builder->addSelect('*');
        }
        DB::statement(DB::raw('set @row=0'));
        $select = DB::raw('@row:=@row+1 as row_no');
        $builder->addSelect($select);
    }
}