Yii2 setDownloadHeaders（）不起作用

Question

码

public function actionExport() {
  ini_set('memory_limit','32M');
  $whileAgo = date('Y-m-d', time() - 2*24*60*60); // 7-9 seems to be the limit for # days before the 30s timeout 
  $agkn = AdGroupKeywordNetwork::find()
    ->select(['field1', 'field2', ...])
    ->where(['>', 'event_date', $whileAgo])->asArray()->each(10000);
  $dateStamp = date('Y-m-d');
  Yii::$app->response->setDownloadHeaders("stats_$dateStamp.csv", 'text/csv');
  echo 'id,ad_group_keyword_id,keyword,network_id,quality,event_date,clicks,cost,impressions,position,ebay_revenue,prosperent_revenue'.PHP_EOL;
  // flush(); // gives us 55s more // doesn't work with gzip
  foreach ($agkn as $row) {
    echo join(',', $row).PHP_EOL;
    // flush();
  }
}

测试：

$ time (curl -sv -b 'PHPSESSID=ckg8l603vpls8jgj6h49d32tq0' http://localhost:81/web/ad-group-keyword-network/export | head)
...
< HTTP/1.1 200 OK
< Transfer-Encoding: chunked
< Content-Type: text/html; charset=UTF-8
<
{ [8277 bytes data]
id,ad_group_keyword_id,keyword,network_id,quality,event_date,clicks,cost,impressions,position,ebay_revenue,prosperent_revenue
9690697,527322,ray ban predator,1,6,2015-11-22,0,0.00,1,5.0,,

它也没有在浏览器中下载CSV文件。它没有设置标题。怎么了？

参考：http://www.yiiframework.com/doc-2.0/yii-web-response.html#setDownloadHeaders()-detail

Answer 1

这是因为php在Yii之前发送了第一个echo的头部。有一些方法可以解决这个问题。

• 将输出收集到缓冲区，然后发送。

      Yii::$app->response->setDownloadHeaders("stats_$dateStamp.csv", 'text/csv');
      $data = 'id,ad_group_keyword_id,keyword,network_id,quality,event_date,clicks,cost,impressions,position,ebay_revenue,prosperent_revenue'.PHP_EOL;
      foreach ($agkn as $row) {
          $data .= join(',', $row).PHP_EOL;
      }
  
      return $data;

• 如果输出太大而无法放入内存，则数据可能会存储到临时文件中。然后发送文件并删除临时文件。在这种情况下，无需手动设置标题。

      $filePath = tempnam(sys_get_temp_dir(), 'export');
      $fp = fopen($filePath, 'w');
      if ($fp) {
          fputs($fp, ...);
      }
      fclose($fp);
  
      return Yii::$app->response->sendFile($filePath, "stats_$dateStamp.csv")
          ->on(\yii\web\Response::EVENT_AFTER_SEND, function($event) {
              unlink($event->data);
          }, $filePath);