autocde2.0/app/Exports/TaskExport.php

<?php

namespace App\Exports;

use App\Models\Task;
use Maatwebsite\Excel\Concerns\FromCollection;
use Maatwebsite\Excel\Concerns\WithHeadings;

class TaskExport implements FromCollection, WithHeadings
{
    private static $index = 1;
    public function collection()
    {
        $tasks = collect([]);

        Task::query()
            ->where("parent_id", 0)
            ->with(['children', 'assignTo', 'createdBy', 'parent', 'requirement', 'project'])
            ->filter(request()->all())
            ->allowed()
            ->orderBy("id")
            ->chunkById(200, function ($items) use (&$tasks) {
                foreach ($items as $item) {
                    $tasks->push($this->formatRow($item));

                    if ($item->children) {
                        foreach ($item->children as $child) {
                            $tasks->push($this->formatRow($child));
                        }
                    }
                }
            });

        return $tasks;
    }

    protected function formatRow(Task $task)
    {
        $displayId = self::$index++;
        return [
            $displayId,
//            $task->id,
            $task->name,
            $task->begin,
            $task->end,
            $task->parent?->name,
            $task->project?->name,
            $task->asset?->name,
            $task->requirement?->name,
            $task->status,
            $task->task_type,
            $task->doc_type,
            $task->suitability,
            $task->state,
            $task->approval_status,
            $task->description,
            $task->createdBy?->name,
            $task->created_at,
        ];
    }

    public function headings(): array
    {
        return [
            'ID',
            'Name',
            'Begin',
            'End',
            'Parent',
            'Project Name',
            'Asset',
            'Requirement',
            'Status',
            'Task Type',
            'Doc Type',
            'Suitability',
            'State',
            'Approval Status',
            'Description',
            'Created By',
            'Created Date',
        ];
    }
}