PHP File Uploading

Uploading files is a common task in web development, and PHP provides a straightforward way to handle file uploads. This guide summarizes the key concepts and steps involved in uploading files using PHP.

Key Concepts

• Form Submission: To upload a file, you need to create an HTML form with the enctype attribute set to multipart/form-data.
• PHP Superglobals: After a file is uploaded, PHP stores the file information in the $_FILES superglobal array.
• File Handling: You can manage and store the uploaded file on the server using functions like move_uploaded_file().

Steps to Upload Files

1. Create an HTML Form

Create a simple HTML form to allow users to select files for upload:

<form action="upload.php" method="post" enctype="multipart/form-data">
    Select file to upload:
    <input type="file" name="fileToUpload" id="fileToUpload">
    <input type="submit" value="Upload File" name="submit">
</form>

2. Process the Upload in PHP

In the upload.php file, use the following PHP code to handle the file upload:

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $target_dir = "uploads/";
    $target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
    $uploadOk = 1;

    // Check if file already exists
    if (file_exists($target_file)) {
        echo "Sorry, file already exists.";
        $uploadOk = 0;
    }

    // Check file size (limit to 500KB for example)
    if ($_FILES["fileToUpload"]["size"] > 500000) {
        echo "Sorry, your file is too large.";
        $uploadOk = 0;
    }

    // Allow certain file formats (e.g., JPG, PNG, PDF)
    $imageFileType = strtolower(pathinfo($target_file, PATHINFO_EXTENSION));
    if(!in_array($imageFileType, ['jpg', 'png', 'pdf'])) {
        echo "Sorry, only JPG, PNG & PDF files are allowed.";
        $uploadOk = 0;
    }

    // Attempt to upload file if all checks are passed
    if ($uploadOk == 1) {
        if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
            echo "The file ". htmlspecialchars(basename($_FILES["fileToUpload"]["name"])). " has been uploaded.";
        } else {
            echo "Sorry, there was an error uploading your file.";
        }
    }
}
?>

Summary of the Code

• $_FILES: Capture the uploaded file's details.
• File Checks: Validate if the file exists, check its size, and restrict file formats.
• move_uploaded_file(): This function moves the uploaded file from its temporary location to the desired directory.

Conclusion

File uploading in PHP is an essential skill for web developers. By following the above steps and understanding the key concepts, beginners can implement file upload functionality in their applications effectively. Always remember to validate and sanitize file uploads to enhance security!