为什么即使我在表单中有 enctype=“多部分/表单数据”，文件也没有在 POST 变量中发送

我正在尝试从已经上传的内容更新图像，但类型文件的输入没有发送，我似乎找不到原因。变量文件上传未被发送。

主.php

<form class="form-horizontal" action="modData.php" method="post" enctype="multipart/form-data">
<div class="form-group">
<label class="control-label col-sm-2 col-lg-offset-2">Image:</label>
    <div class="col-xs-4">
        <?php
            echo '<a href="#"><img src="'.$img.'" alt="img" height="350" width="584"></a>';
        ?>
        <input type="file" class="form-control" id="fileToUpload" name="fileToUpload">
    </div>
</div>
<div class="form-group">
<label class="control-label col-sm-2 col-lg-offset-2">Description:</label>
    <div class="col-xs-8">
        <input name="des" id="des" value="<?php echo $des?>">
        <input type='hidden' name="des2" id="des2" value="<?php echo $des?>">
    </div>
</div>
<button type="submit" class="btn btn-success pull-right" name="save" value="save" id="save">Save</button>
</form>

模组数据.php

if(isset($_POST['fileToUpload'])){
    echo 'file sent!!!';
    $target_dir = "photos/";
    $target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
    echo $target_file;
    $uploadOk = 1;
    $imageFileType = pathinfo($target_file,PATHINFO_EXTENSION);
    // Check if image file is a actual image or fake image
    if(isset($_POST["submit"])) {
        $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
        if($check !== false) {
            echo "File is an image - " . $check["mime"] . ".";
            $uploadOk = 1;
        } else {
            echo "File is not an image.";
            $uploadOk = 0;
        }
    }
    if ($_FILES["fileToUpload"]["size"] > 500000) {
        echo "Sorry, your file is too large.";
        $uploadOk = 0;
    }
    // Allow certain file formats
    if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
    && $imageFileType != "gif" && $imageFileType != "JPG" && $imageFileType != "PNG" && $imageFileType != "JPEG"
    && $imageFileType != "GIF" ) {
        echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
        $uploadOk = 0;
    }
    // Check if $uploadOk is set to 0 by an error
    if ($uploadOk == 0) {
        echo "Sorry, your file was not uploaded.";
    // if everything is ok, try to upload file
    } else {
        $des = $_POST['des'];
        $des2 = $_POST['des2'];
        if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
            $res = mysql_query("UPDATE `image` SET `des`='$des', `img`='".$target_file."' WHERE des='$des2'");
            echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
        } else {
            echo "Sorry, there was an error uploading your file.";
            error_reporting (0);
        }
    }
}
else{
    echo 'Did not send and only doing this';
    $des = $_POST['des'];
    $des2 = $_POST['des2'];
    $res = mysql_query("UPDATE `image` SET `des`='$des' WHERE des='$des2'");
}