PHP / Upload File form - make sure file name is not empty

I have an upload file form and want to check to make sure a filename was selected before proceeding with code to upload.  I keep getting "Undefined index: image ".  

Here is part of the form for the file upload:
    <label for="image">Upload file:</label>
    <input type="hidden" name="MAX_FILE_SIZE" value="<?php echo $max; ?>">
    <input type="file" name="image" id="image">
    <input type="submit" name="upload" id="upload" value="Upload">

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Here is first part of php to check for file upload procedure:

if ( isset ( $_POST['upload'] )) {

	if ( $_POST['image'] !== '' ) {
	

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keith1001Asked:
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keith1001Author Commented:
I think this may be the correct way to get it work or not?

if ( isset ( $_POST['upload'] )) {

	if ( isset ( $_POST['image'] )) {
	

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hieloCommented:
In PHP, all <input type="file"> end up in the $_FILES array, not in $_POST.

// refer to first reference link to read about values in $_FILES['image']['error']
if( isset($_FILES['image']) && $_FILES['image']['error']==UPLOAD_ERR_OK )
{
  // do the processing here.  See the second reference link below.
}

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References:
http://php.net/manual/en/features.file-upload.errors.php
http://www.tizag.com/phpT/fileupload.php
http://php.net/manual/en/features.file-upload.multiple.php
http://www.phpro.org/examples/Multiple-file-upload.html
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Dave BaldwinFixer of ProblemsCommented:
@hielo's links are good.  This page http://php.net/manual/en/features.file-upload.post-method.php has a complete example of the HTML form and the PHP file for receiving the file upload.
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Ray PaseurCommented:
Here is my teaching example that covers most of the things you need to consider in a file upload program.
<?php // demo/upload_single_example.php

/**
 * Demonstrate how to upload a single file in PHP
 *
 * REQUIRED: Man Page References
 * http://php.net/manual/en/reserved.variables.files.php
 * http://php.net/manual/en/features.file-upload.php
 * http://php.net/manual/en/features.file-upload.common-pitfalls.php
 * http://php.net/manual/en/function.move-uploaded-file.php
 *
 * IMPORTANT: If dealing with large files
 * http://php.net/manual/en/ini.core.php#ini.upload-max-filesize
 * http://php.net/manual/en/ini.core.php#ini.post-max-size
 * http://php.net/manual/en/info.configuration.php#ini.max-input-time
 */
error_reporting(E_ALL);

// PHP 5.1+  SEE http://php.net/manual/en/function.date-default-timezone-set.php
date_default_timezone_set('America/Chicago');

// ESTABLISH THE BIGGEST FILE SIZE WE CAN ACCEPT - ABOUT 8 MB
$max_file_size = '8000000';

// ESTABLISH THE KINDS OF FILE EXTENSIONS WE WANT (USE UPPERCASE ONLY)
$file_exts = array
( 'XLS'
, 'XLSX'
, 'PDF'
, 'JPG'
)
;
$f_exts = implode(', ', $file_exts);

// ESTABLISH THE NAME OF THE DESTINATION FOLDER
$my_dir = getcwd();

// OR USE THIS TO PUT UPLOADS IN A SEPARATE FOLDER
$my_dir = 'storage';
if (!is_dir($my_dir))
{
    mkdir($my_dir);
}

// LIST OF THE ERRORS THAT MAY BE REPORTED IN $_FILES[]["error"] (THERE IS NO #5)
$errors = array
( 0 => "Success!"
, 1 => "The uploaded file exceeds the upload_max_filesize directive in php.ini"
, 2 => "The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form"
, 3 => "The uploaded file was only partially uploaded"
, 4 => "No file was uploaded"
, 5 => "UNDEFINED ERROR"
, 6 => "Missing a temporary folder"
, 7 => "Cannot write file to disk"
)
;


// IF THERE IS INFORMATION POSTED
if (!empty($_POST))
{
    // IF THERE ARE ERRORS
    $error_code    = $_FILES["userfile"]["error"];
    if ($error_code)
    {
        trigger_error($errors[$error_code], E_USER_ERROR);
    }

    // GET THE FILE SIZE
    $fsize = number_format($_FILES["userfile"]["size"]);

    // SYNTHESIZE THE NEW FILE NAME FOR TEMPORARY STORAGE
    $fname = basename($_FILES['userfile']['name']);

    // FAIL IF THIS IS NOT AN ALLOWABLE EXTENSION
    $f_ext = explode('.', $fname);
    $f_ext = end($f_ext);
    $f_ext = strtoupper(trim($f_ext));
    if (!in_array($f_ext, $file_exts)) trigger_error("$f_ext NOT ALLOWED.  CHOOSE FROM $f_exts", E_USER_ERROR);

    // THE SERVER PATH TO THE FILE
    $my_path
    = getcwd()
    . DIRECTORY_SEPARATOR
    . $my_dir
    . DIRECTORY_SEPARATOR
    . $fname
    ;

    // THE URL PATH TO THE FILE
    $my_url
    = $my_dir
    . DIRECTORY_SEPARATOR
    . $fname
    ;

    // MESSAGES ABOUT THE UPLOAD STATUS, IF ANY
    $msg = NULL;

    // IF THE FILE IS NEW (DOES NOT EXIST)
    if (!file_exists($my_path))
    {
        // IF THE MOVE FUNCTION WORKED CORRECTLY
        if (move_uploaded_file($_FILES['userfile']['tmp_name'], $my_path))
        {
            $upload_success = 1;
        }
        // IF THE MOVE FUNCTION FAILED IT PROBABLY THREW A MESSAGE
        else
        {
            $upload_success = -1;
            trigger_error("MOVE TO $my_path FAILED", E_USER_ERROR);
        }
    }

    // IF THE FILE ALREADY EXISTS
    else
    {
        $msg .= "<br/><b><i>$my_url</i></b> already exists" . PHP_EOL;

        // SHOULD WE OVERWRITE THE FILE? IF NOT
        if (empty($_POST["overwrite"]))
        {
            $upload_success = 0;
        }

        // IF WE SHOULD OVERWRITE THE FILE, TRY TO MAKE A BACKUP
        else
        {
            $now    = date('Y-m-d-His');
            $my_bak = $my_path . '.' . $now . '.bak';
            if (!copy($my_path, $my_bak))
            {
                $msg .= "<br/><strong>Attempted Backup Failed!</strong>" . PHP_EOL;
            }
            if (move_uploaded_file($_FILES['userfile']['tmp_name'], $my_path))
            {
                $upload_success = 2;
            }
            else
            {
                $upload_success = -1;
                trigger_error("MOVE TO $my_path FAILED", E_USER_ERROR);
            }
        }
    }

    // PREPARE A REPORT OF THE SCRIPT'S SUCCESS OR FAILURE
    if ($upload_success == 2) { $msg .= "<br/>A backup was made and the file was overwritten" . PHP_EOL; }
    if ($upload_success == 1) { $msg .= "<br/><strong>$my_url</strong> has been saved" . PHP_EOL; }
    if ($upload_success == 0) { $msg .= "<br/><strong>It was NOT overwritten.</strong>" . PHP_EOL; }
    if ($upload_success < 0)  { $msg .= "<br/><strong>ERROR: $my_url NOT SAVED - SEE WARNING FROM move_uploaded_file()</strong>" . PHP_EOL; }

    // ADD FILE SIZE AND PERMISSION INFORMATION
    if ($upload_success > 0)
    {
        $msg .= "<br/>$fsize bytes uploaded" . PHP_EOL;
        if (!chmod ($my_path, 0755))
        {
            $msg .= "<br/>chmod(0755) FAILED: fileperms() = ";
            $msg .= substr(sprintf('%o', fileperms($my_path)), -4);
        }
    }

    // SHOW THE SUCCESS OR FAILURE
    echo $msg;

    // SHOW A LINK TO THE FILE
    echo '<br/>'
    . '<a href="'
    . $my_url
    . '" target="_blank">'
    . "See: $my_url"
    . '</a>'
    ;
}


// CREATE THE FORM FOR INPUT (USING HEREDOC SYNTAX)
$form = <<<EOF
<h2>Upload a File</h2>
<p>
<form enctype="multipart/form-data" method="post">
<!--
    SOME IMPORTANT THINGS TO NOTE ABOUT THIS FORM...
    ENCTYPE= ATTRIBUTE IN THE HTML <FORM> TAG
    MAX_FILE_SIZE HIDDEN CONTROL MUST PRECEDE THE FILE INPUT CONTROLS
    INPUT NAME= IN TYPE=FILE DETERMINES THE NAME YOU FIND IN _FILES ARRAY
    ABSENCE OF ACTION= ATTRIBUTE IN <FORM> TAG CAUSES POST TO SAME URL
-->
<input type="hidden" name="MAX_FILE_SIZE" value="$max_file_size" />
Find a file to Upload ($f_exts): <input name="userfile" type="file" />
<br/>Check this box
<input autocomplete="off" type="checkbox" name="overwrite" /> to <strong>overwrite</strong> existing files
</br><input type="submit" value="Upload" />
</form>
</p>
EOF;

echo $form;

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skijCommented:
The original file name from the user's computer can be accessed like this:
$_FILES['image']['name']

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So if you want to make sure that the file name is not empty you could use this:
if(!empty($_FILES['image']['name'])) {
 echo "The file name is not empty";
}

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You may wish to make sure that an actual file was uploaded and you can test for that by checking the file size of what was uploaded:
if(empty($_FILES['image']['size'])) {
 echo "File Not Uploaded";
}

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keith1001Author Commented:
As usual, Ray comes up with best replies.  Ray do you go to any PHP meetups or do any local user groups teaching PHP the proper way.
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Ray PaseurCommented:
Thanks for the points and for your kind words.  I live and work near Washington, DC.  I have taught web development for the local Boston University Center for Digital Imaging Arts, and I participate in the local PHP community -- we have a DC PHP meetup group.  Other than that, I write for E-E and enjoy occasional consulting assignments here and around the world as requirements come up.
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