将数组保存为CSV或XLS文件，并使用Codeigniter下载

Question

如何使用Codeigniter框架将数组保存为文件并将其下载而不先保存在服务器上？

我有两个按钮：

  <button id='csv' class='btn-success btn-sm pull-right'>Pobierz CSV</button>
  <button id='xls' class='btn-success btn-sm pull-right'>Pobierz XLS</button>

然后使用AJAX：

$(document).ready(function () {
    $('#csv').click(function () {
        $.ajax({
            url: window.location + "crawler/metoda",
            type: "POST",
            data: {
                wartosc: 'csv'
            }
        })
    })
    $('#xls').click(function () {
        $.ajax({
            url: window.location + "crawler/metoda",
            type: "POST",
            data: {
                wartosc: 'xls'
            }
        })
    })
});

发送var wartosc切换到metoda方法：

switch($_POST["wartosc"])
{
    case "xls" :
    //code generate .xls file
    exit();

    case "csv" :
    //and here generate .csv
    exit();
}

我尝试了几种解决方案，但它们仅适用于纯php，例如：

<?php
$data = array(
    '0' => array('Key1' => 'value1', 'Key2' => 'value2', 'Key3' => 'value3', 'Key4' => 'value4'),
    '1' => array('Key1' => 'value1', 'Key2' => 'value2', 'Key3' => 'value3', 'Key4' => 'value4'),
    '2' => array('Key1' => 'value1', 'Key2' => 'value2', 'Key3' => 'value3', 'Key4' => 'value4'),
    '3' => array('Key1' => 'value1', 'Key2' => 'value2', 'Key3' => 'value3', 'Key4' => 'value4')
);
$csvName = 'temp.csv';

$fp = fopen($csvName, 'w');
foreach ($data as $line) {
    fputcsv($fp, $line);
}
fclose($fp);

$csvData = file_get_contents($csvName);
header('Content-Type: application/vnd.ms-excel');
header('Content-Length: ' . strlen($csvData));
echo $csvData;
exit;