PHP check if there is a file selected for upload [duplicate]

Question

I have this form and I would like to check if the user has selected a file or not.

<form action="upload.php" method="POST" enctype="multipart/form-data" >
    <select name="category">
        <option value="cat1" name="cat1">Productfotografie</option>
        <option value="cat2" name="cat2">Portretten</option>
        <option value="cat3" name="cat3">Achitectuur</option>
    </select>
    <input type="file" name="file_upload">
    <input type="submit" name="submit" value="Upload photo">
</form>

I wrote this PHP code to test it

if (empty($_POST) === false) {
    $fileupload = $_POST['file_upload'];
    if (empty($fileupload) === true) { //
            echo "Error no file selected";     
    } else {
        print_r($_FILES);
    }
} 

But I get the "Error no file selected" even if I DO select something. Any clue? I'm sorry I'm really new in PHP.

EDIT: I already tried replacing $fileupload = $_FILES['file_upload'] but it prints an empty error

(Array ( [file_upload] => Array ( [name] => [type] => [tmp_name] => [error] => 4 [size] => 0 ) ))

when I do NOT enter a file?

Answer 1

Use the $_FILES array and the UPLOAD_ERR_NO_FILE constant:

if(!isset($_FILES['file_upload']) || $_FILES['file_upload']['error'] == UPLOAD_ERR_NO_FILE) {
    echo "Error no file selected"; 
} else {
    print_r($_FILES);
}

You can also check UPLOAD_ERR_OK which indicates if the file was successfully uploaded (present and no errors).

Note: you cannot use empty() on the $_FILES['file_upoad'] array, because even if no file is uploaded, the array is still populated and the error element is set, which means empty() will return false.