javascript - 为什么 PHP 找不到使用 JS 或 jQuery 可访问的元素？

Question

我已经盯着这个问题好几个小时了。对于我的一生，我找不到解释。 PHP 找不到 userid 和 subgenre 元素。其他的都找到了。

HTML 表单

<form action="php/writers.php" method="post" enctype="multipart/form-data" target="upload-target" onsubmit="startUpload();" >
    <h1>Writers</h1>
    <p>
        <input id="title" name="title" class="form-control"  placeholder="Title" required autofocus="true" />
    </p>
    <p>
        <label for="work-type" class="fixed50">Form:</label>
        <select id="work-type" name="work-type">
            <option value="fiction">Fiction</option>
            <option value="non-fiction">Non-Fiction</option>
            <option value="screenplay">Screenplay</option>
            <option value="play">Play</option>
        </select>
    </p>
    <p>
        <p>For an explanation of the genres shown here, see <a target="_blank" href="https://en.wikipedia.org/wiki/List_of_genres">List of genres</a></p>
        <label for="genre"  class="fixed50">Genre:</label>
        <select id="genre" name="genre">
        </select>
    </p>
    <p>
        <label for="subgenre" class="fixed50">Sub-Genre:</label>
        <select id="subgenre" name="subgenre">`
            <option value="0">None</option>
        </select><br/>
    </p>
    <p>
        <label for="nbrPages" class="fixed50">Number of pages:</label>
        <input id="nbrPages" name="nbrPages" required style="width: 48px" placeholder="Pages" /><br/>
    </p>
    <p>For a limied time, writers can upload their sysnopsis or query letterr for <span style="color: #f00; font-weight:bold">FREE</span>. We reserve the right to change this policy without notice.</p>
    <div id="tips">The objective of a sysnopsis or query letter is to entice enablers into requesting your manuscript. 
                    It must be brief and to the point, now more than twp pages and, of course very well written.
    </div>
    <div class="form-group">
        <p id="file-warning">Your synopsis or query letter must be a PDF file.
        <a target="_blank" href="https://www.freepdfconvert.com/" target="_blank">Free file conversion to PDF</a></p>
    </div>
    <div class="form-group">
        <label for="file2upload">PDF to Upload</label>
        <input id="file2upload" name="file2upload" type="file" required value="File to upload" />
    </div>
    <div id="recaptcha-elements"></div>
    <div class="form-group">
        <button type="submit" id="writers-submit" class="btn btn-default">Submit</button>
    </div>
    <input id="userid" name="userid" type="hidden" />
    <iframe id="upload-target" name="upload-target" src="#" ></iframe>                 
</form>

以下 JS 函数将正确的值写入控制台。

JS

function startUpload() {
    $("#userid").val(window.localStorage.getItem('user-id'));
    console.log("jquery val=" + $("#subgenre").val());
    console.log("getElementById value=" + document.getElementById('subgenre').value);
    showMessage(1, "Uploading...");
    return true;
}

控制台日志

userid=51 VM39985:122

jquery val=0 VM39985:123

getElementById value=0

/php/writers.php:1 POST 500 (Internal Server Error)

PHP

$uploadDirectory = '/home/deje/public_html/writers-tryst/uploads/'; //specify upload directory ends with / (slash)
require_once "dbconnect.php";
$result = 0;
$File_Name          = basename($_FILES['file2upload']['name']);
$File_Ext           = substr($File_Name, strrpos($File_Name, '.')); //get file extention
$Random_Number      = rand(0, 9999999999); //Random number to be added to name.
$NewFileName        = $Random_Number.$File_Ext; //new file name

var_dump($_REQUEST); 
$target_path = $uploadDirectory . $NewFileName;

if (@move_uploaded_file($_FILES['file2upload']['tmp_name'], $target_path)) {
    $finfo = finfo_open(FILEINFO_MIME_TYPE);
    $mime_type = finfo_file($finfo, $uploadDirectory . $NewFileName);
    finfo_close($finfo); 
    if ($mime_type != 'application/pdf') {
        unlink($UploadDirectory . $NewFileName);
        $data = array('File MUST be a PDF!');
        $result = 0;
    } else $result = 1;
}
if (!isset($_REQUEST["title"]) || empty(trim($_REQUEST["title"])))
    throw new Exception('You must enter a title.');       
else {
    $title = filter_var(trim($_REQUEST["title"]), FILTER_SANITIZE_STRING);
    $title = htmlspecialchars_decode($title, ENT_QUOTES);
}
if (!isset($_REQUEST["userid"]) || empty(trim($_REQUEST["userid"])))
    throw new Exception('Userid is missing.');       
else {
    $userrid = filter_var(trim($_REQUEST["userid"]), FILTER_SANITIZE_STRING);
    $userid = htmlspecialchars_decode($userid, ENT_QUOTES);
}
if (!isset($_REQUEST["work-type"]) || empty(trim($_REQUEST["work-type"])))
    throw new Exception('You must enter a work type.');       
else {
    $worktype = filter_var(trim($_REQUEST["work-type"]), FILTER_SANITIZE_STRING);
    $worktype = htmlspecialchars_decode($worktype, ENT_QUOTES);
}
if (!isset($_REQUEST["genre"]) || empty(trim($_REQUEST["genre"])))
    throw new Exception('You must enter a title.');       
else {
    $genre = filter_var(trim($_REQUEST["genre"]), FILTER_SANITIZE_STRING);
    $genre = htmlspecialchars_decode($genre, ENT_QUOTES);
}
if (!isset($_REQUEST["subgenre"]) || empty(trim($_REQUEST["subgenre"])))
    throw new Exception('You must enter a sub-genre.');       
else {
    $subgenre = filter_var(trim($_REQUEST["subgenre"]), FILTER_SANITIZE_STRING);
    $subgenre = htmlspecialchars_decode($subgenre, ENT_QUOTES);
}
if (!isset($_REQUEST["nbrPages"]) || empty(trim($_REQUEST["nbrPages"])))
    throw new Exception('You must enter the number of pages your work contains.');       
else {
    $nbrPages = filter_var(trim($_REQUEST["nbrPages"]), FILTER_SANITIZE_STRING);
    $nbrPages = htmlspecialchars_decode($nbrPages, ENT_QUOTES);
}

$dbh = connect2DB();
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$stmt = $dbh->prepare(
    "INSERT Writers(fkAccounts, Title, WorkType, Genre, SubGenre, Filename) 
    VALUES(:fk, :title, :worktype, :genre, :subgenre, :filename)"
);

$stmt->bindParam(':fk', $userid, PDO::PARAM_INT, 10);
$stmt->bindParam(':title', $title, PDO::PARAM_STR, 255);
$stmt->bindParam(':worktype', $worktype, PDO::PARAM_STR, 30);
$stmt->bindParam(':genre', $genre, PDO::PARAM_STR, 100);
$stmt->bindParam(':subgenre', $subgenre, PDO::PARAM_STR, 100);
$stmt->bindParam(':filename', $NewFileName, PDO::PARAM_STR, 30);

$stmt->execute();


echo "<script type='text/javascript'>stopUpload(" . $result . ");</script>";
sleep(1);
exit();

$data = array();
require_once 'cookies.php';

if (isset($_REQUEST['files'])) {  
    $error = false;
    $files = array();

    foreach ($_FILES as $file) {
        if ($file["size"] > $filesize_limit) {
//            $data = array('Maximum file size (' . $filesize_limit . ') exeeded.');
//            $error = true;
        } else {
            $File_Name          = basename($file['name']);
            $File_Ext           = substr($File_Name, strrpos($File_Name, '.')); //get file extention
            $Random_Number      = rand(0, 9999999999); //Random number to be added to name.
            $NewFileName        = $Random_Number.$File_Ext; //new file name

            if (move_uploaded_file($file['tmp_name'], $UploadDirectory . $NewFileName)) {
                $files[] = $UploadDirectory . $file['name']; //$NewFileName; // 
                $finfo = finfo_open(FILEINFO_MIME_TYPE);
                $mime_type = finfo_file($finfo, $UploadDirectory . $NewFileName);
                //$data = array('Mime-Type (' . $mime_type . ')');
                finfo_close($finfo); 
                if ($mime_type != 'application/pdf') {
                    unlink($UploadDirectory . $NewFileName);
                    $data = array('File MUST be a PDF!');
                    $error = true;
                };
            } else {
                $error = true;
            }
        }
    }
    if ($error) {
        $data = array('error' => $data);
    } else {
        $data = array('files' => $files);
    }
} else {
    $data = array('success' => 'Form was submitted', 'formData' => $_REQUEST);
};

echo json_encode($data);

PHP 错误日志

[17-May-2016 00:59:49 UTC] PHP Notice: Undefined variable: userid in /home/deje/public_html/writers-tryst/php/writers.php on line 34

[17-May-2016 00:59:49 UTC] PHP Stack trace:

[17-May-2016 00:59:49 UTC] PHP 1. {main}() /home/deje/public_html/writers-tryst/php/writers.php:0

[17-May-2016 00:59:49 UTC] PHP Fatal error: Uncaught exception 'Exception' with message 'You must enter a sub-genre.' in /home/deje/public_html/writers-tryst/php/writers.php:49

Stack trace:

0 {main} thrown in /home/deje/public_html/writers-tryst/php/writers.php on line 49

Answer 1

首先，您在这两行中将一个不存在的变量传递给一个函数

$userrid = filter_var(trim($_REQUEST["userid"]), FILTER_SANITIZE_STRING);
$userid = htmlspecialchars_decode($userid, ENT_QUOTES);

当您调用 htmlspecialchars_decode 时，未定义 $userid，这是您可能打算输入的错字

$userrid = filter_var(trim($_REQUEST["userid"]), FILTER_SANITIZE_STRING);
$userid = htmlspecialchars_decode($userrid, ENT_QUOTES);

第二个错误是 PHP 抛出这一行

if (!isset($_REQUEST["subgenre"]) || empty(trim($_REQUEST["subgenre"])))
    throw new Exception('You must enter a sub-genre.');       

那是因为条件很严格。
名为 subgenre 的 select 元素的值为 0，在 PHP 中 empty(trim("0")); 是真实的，因此 if 条件进入，并抛出异常。