无法使用ajax上传多个文件

Question

First of all this might be a silly question as there are many topics available on this but seriously I am not being able to get it straight and understand how to make it work.

WHAT I AM TRYING TO DO

I am trying to upload multiple files using AJAX and PHP.

PROBLEM

• I cant figure out how to pass the data to the PHP script using AJAX. I don't want to use a form and a submit button for uploading.
• Tried using a form and submitting it using jQuery still couldn't make it.

HTML

<div id="content">
    <div id="heading">Upload your files seamlessly</div>
    <a href="#"><div id="upload" class="button" title="Upload your files"><i class="fa fa-cloud-upload fa-align-center" aria-hidden="true"></i>
</div></a>
    <a href="view.php"><div id="view" class="button" title="View all files on my cloud"><i class="fa fa-eye fa-align-center" aria-hidden="true"></i>
</div></a>
</div>

<form id="fileupload" method="POST" enctype="multipart/form-data">
<input type="file" multiple name="uploadfile[]" id="uploadfile" />
</form>

JS

<script type="text/javascript">
$(document).ready(function(){
    $('#upload').click(function(){
        $('input[type=file]').click();
        return false;
    });

    $("#uploadfile").change(function(){
         //submit the form here  
         $('#fileupload').submit();
    });
});
</script>

PHP

<?php
if(isset($_FILES['uploadfile'])){

    $errors= array();

    foreach($_FILES['uploadfile']['tmp_name'] as $key => $tmp_name ){
        $file_name = $key.$_FILES['uploadfile']['name'][$key];
        $file_size =$_FILES['uploadfile']['size'][$key];
        $file_tmp =$_FILES['uploadfile']['tmp_name'][$key];
        $file_type=$_FILES['uploadfile']['type'][$key]; 
        if($file_size > 2097152){
            $errors[]='File size must be less than 2 MB';
        }       

        //$query="INSERT into upload_data (`USER_ID`,`FILE_NAME`,`FILE_SIZE`,`FILE_TYPE`) VALUES('$user_id','$file_name','$file_size','$file_type'); ";

        $desired_dir="storage";

        if(empty($errors)==true){
            if(is_dir($desired_dir)==false){
                mkdir("$desired_dir", 0700);        // Create directory if it does not exist
            }

            if(is_dir("$desired_dir/".$file_name)==false){
                move_uploaded_file($file_tmp,"$desired_dir/".$file_name);
            }
            else{                                   // rename the file if another one exist
                $new_dir="$desired_dir/".$file_name.time();
                 rename($file_tmp,$new_dir) ;               
            }
         //mysql_query($query);         
        }
        else{
                print_r($errors);
        }
    }
    if(empty($error)){
        echo "Success";
    }
}
?>

Any help would be appreciated.

Answer 1

This is a very simple example of what you want to do.

HTML

Wrap your inputs within a form. Why? Because it is the easiest way to do it.

<form action="process.php" method="post">
    <input type="file" multiple name="uploadfile[]">
    <input type="submit" value="Upload"> 
</form>

JavaScript

Attach an onsubmit event handler to your form. Use $.ajax() to send a POST request.

Pass your form element i.e. this into the constructor of a FormData object and use it as your data when you send the request as shown below. You need to make sure that you set processData and contentType as false also for this to work.

$(function () {
    $('form').on('submit', function (e) {
        e.preventDefault();
        // send request
        $.ajax({
            url: this.action, 
            type: this.method, 
            data: new FormData(this), // important
            processData: false, // important 
            contentType: false, // important
            success: function (res) {
                alert(res);
            }
        });
    });
});

PHP (process.php)

Let's clean up your PHP.

<?php
// always a good idea to turn on errors during development
error_reporting(E_ALL);
ini_set('display_errors', 1);

$dir = './storage';
$errors = [];

if (isset($_FILES['uploadfile'])) {
    $files = $_FILES['uploadfile'];
    // create directory if it does not exist
    !is_dir($dir) && mkdir($dir, 0700);
    // validate & upload files
    foreach (array_keys($files['tmp_name']) as $key) {
        $file = [
            'name' => $files['name'][$key],
            'size' => $files['size'][$key],
            'tmp_name' => $files['tmp_name'][$key],
            'type' => $files['type'][$key],
            'error' => $files['error'][$key]
        ];
        // skip if no file was given
        if ($file['error'] === UPLOAD_ERR_NO_FILE) {
            continue;
        }
        // get file extension
        $file['ext'] = strtolower(pathinfo($file['name'], PATHINFO_EXTENSION));
        // generate a unique name (!)
        $file['name'] = uniqid() . '.' . $file['ext'];
        // validate
        if (!file_exists($file['tmp_name']) || 
            !is_uploaded_file($file['tmp_name']) ||
            $file['error'] !== UPLOAD_ERR_OK) {
            $errors[$key] = 'An unexpected error has occurred.';
        } elseif ($file['size'] > 2097152) {
            $errors[$key] = 'File size must be less than 2 MB';
        // upload file
        } elseif (!move_uploaded_file($file['tmp_name'], $dir . '/' . $file['name'])) {
            $errors[$key] = 'File could not be uploaded.';
        }
    }
}

if ($errors) {
    print_r($errors);
} else {
    echo 'no errors';
}
?>

(!) Do keep in mind that uniqid() is actually not unique.