Serialization of 'Doctrine\DBAL\Driver\PDOConnection' is not allowed - php

Question

I'm working on a project
and I made an exportable class
this is the class
I'm sending a query to exportal tyope of 'Illuminate\Database\Eloquent\Builder'
<?php
namespace App\Exports;
use Maatwebsite\Excel\Concerns\FromQuery;
use Maatwebsite\Excel\Concerns\Exportable;
use Maatwebsite\Excel\Concerns\WithMapping;
use Illuminate\Contracts\Queue\ShouldQueue;
use Maatwebsite\Excel\Concerns\WithHeadings;
class ExcelExport implements FromQuery, WithMapping, WithHeadings
{
use Exportable;
private $query;
public function __construct($query)
{
$this->query = $query;
}
public function query()
{
return $this->query;
}
public function headings():array
{
$return = [
'H1',
'H2',
];
return $return;
}
public function map($row):array
{
$return = [];
foreach ($row->relation as $rel) {
$return[] = $rel->column;
}
return $return;
}
}
and call it into my controller as
public function export(Request $request, string $type = 'excel')
{
// returns Builder
$query = $this->service->findByReportable($request, 1);
$file = new ExcelExportLead($query);
if ($file){
switch (strtolower($type)) {
case 'pdf':
$file_name = 'export-' . time() . '.pdf';
// OriginExcel refers to 'Maatwebsite\Excel\Excel'
return $file::queue($file, $file_name, OriginExcel::DOMPDF);
break;
default:
$file_name = 'export-' . time() . '.xls';
return $file->queue($file_name);
break;
}
} else{
return back()->withErrors(__('common.Sorry But there Was an issue in exporting Data please try again'));
}
But there the error appeared is 'Serialization of 'Doctrine\DBAL\Driver\PDOConnection' is not allowed'
i don't know how to solve it I've used SerializesModels but it didn't fix the issue

Answer 1

Serialization it's a tool where you encode a variable/object into a text (or binary) representation to then move that variable to another thread/process.
The underlying problem it's that the Builder object has a PDOConnection attribute (the connection to the database) and those objects by definition can't be serialized, as they are usually a file descriptor in the operating system that can't be moved to another process/thread.
The solution should go along the lines of either
Sending the query as a string to ExcelExport using the builder->toSql() method
Encoding the query in some other way (IE anourvalar/eloquent-serialize https://packagist.org/packages/anourvalar/eloquent-serialize).