workHour/app/Exports/ResearchExpenseMultipleSheetExport.php

<?php

namespace App\Exports;

use Maatwebsite\Excel\Concerns\WithMultipleSheets;

class ResearchExpenseMultipleSheetExport implements WithMultipleSheets
{
    protected $sheetsData;

    /**
     * @param array $sheetsData 现在的格式应该是：
     * [
     * '2025-RD01' => ['project' => [...], 'data' => [...]],
     * '2025-RD02' => ['project' => [...], 'data' => [...]]
     * ]
     */
    public function __construct(array $sheetsData)
    {
        $this->sheetsData = $sheetsData;
    }

    public function sheets(): array
    {
        $sheets = [];
        foreach ($this->sheetsData as $sheetTitle => $content) {
            // 将每一个唯一的 Key (年份-项目) 传给具体的 Sheet 类
            $sheets[] = new ResearchExpenseSheetExport(
                (string)$sheetTitle, // 这里的 title 会显示在 Excel 标签页上
                $content['data'],
                $content['project'] ?? []
            );
        }
        return $sheets;
    }
}