Laravel 8中Maatwebsite\Excel 3.1导出代码改写求助

1. 创建导出类 #

在app/Exports目录下创建InstanceExport.php文件（若目录不存在则手动创建），内容如下：

<?php

namespace App\Exports;

use Maatwebsite\Excel\Concerns\FromQuery;
use Maatwebsite\Excel\Concerns\WithHeadings;
use Maatwebsite\Excel\Concerns\WithMapping;
use Maatwebsite\Excel\Concerns\WithChunkReading;

class InstanceExport implements FromQuery, WithHeadings, WithMapping, WithChunkReading
{
    protected $requested;
    protected $query;

    public function __construct(array $requested, $query)
    {
        $this->requested = $requested;
        $this->query = $query;
    }

    // 返回查询构建器
    public function query()
    {
        return $this->query;
    }

    // 自定义表头
    public function headings(): array
    {
        $columns = [];
        foreach ($this->requested as $column) {
            switch ($column) {
                case 'sku':
                    $columns[] = 'SKU';
                    break;
                case 'material_name':
                    $columns[] = 'Material Name';
                    break;
                case 'new_or_used':
                    $columns[] = 'NEW OR USED';
                    break;
                case 'barcode':
                    $columns[] = 'BARCODE';
                    break;
                case 'asset_or_sale':
                    $columns[] = 'ASSET OR SALE';
                    break;
                case 'cost':
                    $columns[] = 'COST';
                    break;
                case 'last_stock':
                    $columns[] = 'LAST STOCK';
                    break;
                default:
                    $columns[] = strtoupper($column);
                    break;
            }
        }
        return $columns;
    }

    // 映射每行数据
    public function map($instance): array
    {
        $row = [];
        $locale = app()->getLocale();
        
        foreach ($this->requested as $column) {
            switch ($column) {
                case 'sku':
                    $row[] = '[' . (string)$instance->sku . ']';
                    break;
                case 'material_name':
                    $row[] = empty($instance->Material) ? '------' : (string)$instance->Material->{"name_$locale"};
                    break;
                case 'new_or_used':
                    $row[] = $instance->is_new == 'Y' ? 'NEW' : 'secondhand';
                    break;
                case 'barcode':
                    $row[] = '[' . (string)$instance->barcode . ']';
                    break;
                case 'asset_or_sale':
                    $row[] = $instance->is_asset == 'Y' ? 'ASSET' : ' not asset';
                    break;
                case 'cost':
                    $row[] = (string)round($instance->cost_of_good_sold, 2);
                    break;
                case 'last_stock':
                    if (empty($instance->LastOrderEntry)) {
                        $row[] = '------';
                    } else {
                        $row[] = $instance->LastOrderEntry->Stock ? (string)$instance->LastOrderEntry->Stock->{"name_$locale"} : '------';
                    }
                    break;
                default:
                    $row[] = '------';
                    break;
            }
        }
        return $row;
    }

    // 设置分块大小，和旧代码保持一致
    public function chunkSize(): int
    {
        return 500;
    }
}

2. 修改控制器中的导出代码 #

替换原有的闭包导出逻辑，改为调用导出类：

ini_set("memory_limit", "-1");
$requested = (array) $request->columns_to_export;

// 预加载关联模型优化性能（可选）
$query = $this->data['query']->with(['Material', 'LastOrderEntry.Stock']);

return Excel::download(new \App\Exports\InstanceExport($requested, $query), 'instances-' . date('Y-m-d') . '.xlsx');

关键改动说明 #

• 3.1版本采用导出类模式替代旧版闭包写法，贴合Laravel面向对象设计
• 通过WithChunkReading接口自动实现分块查询，无需手动调用chunk()方法
• 拆分表头和行数据逻辑到WithHeadings、WithMapping接口，代码结构更清晰
• 修正旧代码中的拼写错误（Material Nmae→Material Name、ASSEST OR SALE→ASSET OR SALE）
• 可选预加载关联模型，避免N+1查询，提升导出效率

内容的提问来源于stack exchange，提问作者OMAR R A SHAIKHOMAR