为什么$ _FILES []总是为空? [英] Why is $_FILES[] always empty?

问题描述

我正在尝试使用Php和Javascript制作AJAX文件上传器.我遇到的问题是在我尝试使用 move_uploaded_file 函数， $ _ FILES 数组的 upload.php 脚本中始终为空.

I'm trying to make an AJAX file uploader with Php and Javascript. The problem I'm having is that in my upload.php script where I'm trying to use the move_uploaded_file function, the $_FILES array is always empty.

• 在/etc/php/7.2/apache2/php.ini
中选中的 file_uploads = On
• 检查了 uploader.php 和 upload.php
的当前工作目录
• 检查了上传
的文件权限
• 更改了/etc/php/7.2/apache2/php.ini
中的 uploads_tmp_dir

uploader.php中的HTML:

<form class="form" id="upload_form">
    <input type="file" name="file_to_upload" id="file_to_upload"><br>
    <input class="button" type="submit" value="Upload">
</form>

uploader.php中的Javascript:

<script>
  var upload_form    = document.getElementById('upload_form');
  var file_to_upload = document.getElementById('file_to_upload');

  upload_form.addEventListener("submit", upload_file);

  function upload_file (e) {
    e.preventDefault();

    var xhr = new XMLHttpRequest()
    xhr.open("POST", "upload.php");
    xhr.setRequestHeader("Content-Type", "multipart/form-data");
    xhr.send(new FormData(upload_form));
  }
</script>

upload.php:

<?php
//$target_path = "uploads/".basename($_FILES["file_to_upload"]["name"]);
$uploaded_file = $_FILES['file_to_upload']['tmp_name'];
var_dump($_FILES); // This is always array(0) { }

if(file_exists($uploadedFile)) {
   echo "file uploaded to temp dir";
} else {
   echo "file upload failed"; // This is always the outcome
}
//move_uploaded_file($_FILES["file_to_upload"]["tmp_name"], $target_path);
?>

推荐答案

根据.您还必须指定 method ="post" -请参阅以下答案一个解释.

According to the PHP docs, you must specify enctype="multipart/form-data". You must also specify method="post" -- see this answer for an explanation.

因此，您的< form> 应该显示为:

So your <form> should read:

<form class="form" id="upload_form" enctype="multipart/form-data" method="post">

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