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How do I use the $_FILES superglobal to access uploaded file information?
How do I use the $_FILES superglobal to access uploaded file information?
Jun 20, 2025 am 01:07 AM
To effectively handle file uploads in PHP, you need to perform the following steps in turn: first check whether the file is uploaded successfully, and determine whether $_FILES['fileToUpload']['error'] is equal to UPLOAD_ERR_OK; secondly, understand the file information contained in the $_FILES array, such as name, type, tmp_name, error and size; then, use the move_uploaded_file() function to move the file from the temporary path to the specified directory, and ensure that the target directory is writable and the file name is safe; finally, if you need to support multiple file uploads, you should set the name attribute to an array form in HTML, and traverse each file in PHP. Only by correctly using $_FILES and combining verification and security measures can the complete file upload process be completed.
When you're handling file uploads in PHP, the $_FILES superglobal is where you'll find all the details about the uploaded file. It contains information like the file name, type, size, temporary storage path, and any errors that occurred during the upload.
Here's how to use it effectively:
Check if a File Was Uploaded
Before doing anything with $_FILES , make sure a file was actually uploaded. You can check this by looking at the error key. If it's set to UPLOAD_ERR_OK , then the upload was successful.
if ($_FILES['fileToUpload']['error'] === UPLOAD_ERR_OK) {
// Proceed with handling the file
} Note: The index 'fileToUpload' corresponds to the name attribute of your HTML input element:
<input type="file" name="fileToUpload">
Also keep in mind that for file uploads to work properly, your form must have the attribute enctype="multipart/form-data" .
Understand What $_FILES Contains
Each uploaded file will give you an array with these keys:
-
name– the original name of the file on the user's computer -
type– the MIME type (not always reliable) -
tmp_name– the temporary filename stored on the server -
error– any error code from the upload process -
size– the size of the uploaded file in bytes
For example:
echo 'Original Name: ' . $_FILES['fileToUpload']['name']; echo 'Size: ' . $_FILES['fileToUpload']['size'] . ' bytes'; echo 'Temporary Path: ' . $_FILES['fileToUpload']['tmp_name'];
You might want to log or inspect the contents of $_FILES while debugging:
print_r($_FILES);
Move the Uploaded File to a Permanent Location
Uploaded files are stored in a temporary directory and will be deleted at the end of the request unless you move them.
Use move_uploaded_file() to save the file permanently:
$uploadDir = 'uploads/';
$uploadFile = $uploadDir . basename($_FILES['fileToUpload']['name']);
if (move_uploaded_file($_FILES['fileToUpload']['tmp_name'], $uploadFile)) {
echo "File is valid and was uploaded successfully.";
} else {
echo "Possible file upload attack!";
}A few things to watch out for:
- Make sure the target directory exists and is writable by the web server.
- Avoid using user-provided filenames directly — sanitize or rename them to prevent overwriting existing files or security issues.
- Consider checking the file type or limiting the maximum upload size via PHP settings (
upload_max_filesize,post_max_size) or script-level checks.
Handle Multiple File Uploads
If you allow users to upload multiple files, you need to structure your input like this:
<input type="file" name="filesToUpload[]" multiple>
Then loop through the $_FILES array:
foreach ($_FILES['filesToUpload']['name'] as $index => $name) {
$tmpName = $_FILES['filesToUpload']['tmp_name'][$index];
if (is_uploaded_file($tmpName)) {
move_uploaded_file($tmpName, "uploads/" . $name);
}
}This way, each selected file gets processed individually.
That's basically how you use $_FILES . It gives you all the info you need, but you still have to handle moving, validating, and securing the upload yourself.
The above is the detailed content of How do I use the $_FILES superglobal to access uploaded file information?. For more information, please follow other related articles on the PHP Chinese website!
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