How Can I Verify If a File Was Uploaded in PHP?

PHP File Upload Optional Check

When performing form validation, it's crucial to verify that the user has uploaded a file, especially when the upload is optional. Neglecting this can lead to unnecessary validation efforts, potentially compromising security.

Checking File Upload Status

To determine whether a file has been uploaded, you can utilize the is_uploaded_file() function. This function returns TRUE if the specified file was uploaded through an HTTP POST request. This is a crucial step to prevent malicious actors from exploiting the script to operate on files they should not have access to.

<code class="php">if (!file_exists($_FILES['myfile']['tmp_name']) || !is_uploaded_file($_FILES['myfile']['tmp_name'])) {
    echo 'No upload';
}</code>

This snippet checks if the file named myfile exists and then confirms its upload status. If either condition fails, it indicates that no file was uploaded.

Using a FileUpload Class

In a more complex scenario, you can employ a class to encapsulate the file upload process. Here's an example:

<code class="php">class FileUpload {
    // ... (other methods here)

    public function fileUploaded() {
        if (empty($_FILES)) {
            return false;
        }
        $this->file = $_FILES[$this->formField];
        if (!file_exists($this->file['tmp_name']) || !is_uploaded_file($this->file['tmp_name'])) {
            $this->errors['FileNotExists'] = true;
            return false;
        }
        return true;
    }
}</code>

This class provides a convenient way to determine the file's existence and upload status, handling the necessary checks internally.

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