PHP多文件上传失败求助：含缩略图生成与重命名，需保留4个input

Let's break down the problems in your code and fix them step by step:

1. Invalid HTML: Duplicate IDs #

All four file inputs share the same ID upload-image-three. IDs must be unique in HTML—this can break your readURL function and cause unexpected behavior. Update each input to have a unique ID:

<input type="file" name="files[]" id="upload-image-1" onchange="readURL(this);">
<input type="file" name="files[]" id="upload-image-2" onchange="readURL(this);">
<input type="file" name="files[]" id="upload-image-3" onchange="readURL(this);">
<input type="file" name="files[]" id="upload-image-4" onchange="readURL(this);">

2. Incorrect File Size Validation #

Your code checks for files larger than 2000 MB instead of 2 MB. Fix the size limit:

// 2 MB = 2 * 1024 * 1024 = 2097152 bytes
if ($file_size > 2097152) {
    $errors[] = 'File size must be less than 2 MB';
}

3. Missing Upload Error Handling #

You’re not checking for built-in PHP upload errors, which are critical for diagnosing failures. Add this check inside your file loop:

$file_error = $_FILES['files']['error'][$key];
if ($file_error !== UPLOAD_ERR_OK) {
    switch ($file_error) {
        case UPLOAD_ERR_INI_SIZE:
            $errors[] = 'File exceeds php.ini upload limit';
            break;
        case UPLOAD_ERR_FORM_SIZE:
            $errors[] = 'File exceeds form upload limit';
            break;
        case UPLOAD_ERR_PARTIAL:
            $errors[] = 'File was only partially uploaded';
            break;
        case UPLOAD_ERR_NO_FILE:
            $errors[] = 'No file was selected for upload';
            break;
        case UPLOAD_ERR_CANT_WRITE:
            $errors[] = 'Failed to write file to disk (permission issue?)';
            break;
        default:
            $errors[] = 'Unknown upload error occurred';
    }
}

4. Permission & Directory Issues #

Ensure your upload/ and thumb/ directories:

• Exist (your code creates upload/ but not thumb/—add mkdir("thumb/", 0755); if needed)
• Are writable by the web server user (set permissions to 755 or adjust ownership to match your server’s user, e.g., www-data)

5. Thumbnail Generation Inefficiency #

Your current code regenerates thumbnails for every image in upload/ on every submission. Instead, generate thumbnails immediately after uploading each new file:

// After move_uploaded_file succeeds:
$source = $desired_dir . $file_name . $sExt;
$dest = "thumb/" . $file_name . $sExt;
generateThumbnail($source, $dest, 100, 100);

// Add this helper function outside your loop:
function generateThumbnail($source, $dest, $nw, $nh) {
    $size = getimagesize($source);
    $w = $size[0];
    $h = $size[1];
    
    $stype = explode(".", $source);
    $stype = strtolower(end($stype));
    
    switch ($stype) {
        case 'gif':
            $simg = imagecreatefromgif($source);
            break;
        case 'jpg':
            $simg = imagecreatefromjpeg($source);
            break;
        case 'png':
            $simg = imagecreatefrompng($source);
            break;
        default:
            return false;
    }
    
    $dimg = resizePreservingAspectRatio($simg, $nw, $nh);
    imagepng($dimg, $dest);
    imagedestroy($simg);
    imagedestroy($dimg);
    return true;
}

6. Unsafe & Unnecessary eval() Usage #

Creating variables like $file1 with eval() is risky and unnecessary. Use an array instead:

$uploadedFiles = [];
// After successful upload:
$uploadedFiles[] = $file_name . $sExt;
// Later, use $uploadedFiles[0], $uploadedFiles[1], etc., in your database query

7. Incomplete Code Fix #

Your provided code cuts off mid-database insert. Ensure all form fields are properly closed in your execute() call, e.g.:

$stmt->execute(array(
    ':title' => filter_input(INPUT_POST, 'title'),
    ':brand' => filter_input(INPUT_POST, 'brand'),
    ':model' => filter_input(INPUT_POST, 'model'),
    ':kmdriven' => filter_input(INPUT_POST, 'kmdriven'),
    ':price' => filter_input(INPUT_POST, 'price'),
    ':nego' => filter_input(INPUT_POST, 'nego'),
    ':year' => filter_input(INPUT_POST, 'year'),
    ':addes' => filter_input(INPUT_POST, 'addes'),
    ':sname' => filter_input(INPUT_POST, 'sname'),
    ':smail' => filter_input(INPUT_POST, 'smail'),
    ':sphone' => filter_input(INPUT_POST, 'sphone')
));

Final Notes #

• Always validate file types using server-side checks (don’t rely solely on client-side MIME types). Use finfo_file to detect actual file content for better security.
• Enable PHP error reporting (error_reporting(E_ALL); ini_set('display_errors', 1);) temporarily to see any hidden errors during testing.

内容的提问来源于stack exchange，提问作者sanoj lawrence