PHP code not going inside my foreach loop

Question

I have the following code basically I am deleting one or more rows from a database selected using checkboxes and also then deleting the associated images from the server using PHP's unlink() function:

if(isset($_POST["delete"])){

    $checkbox = $_POST['checkbox'];

    foreach($checkbox as $id) {

        print "here 1";

        $wpdb->query("DELETE FROM `gate_options` WHERE `id` = $id LIMIT 1");

        print "here 2 after delete row in db";

    }

    $myrows = $wpdb->get_results("SELECT `image_path` FROM `gate_options` WHERE `id` = $id LIMIT 1");

    print "here 3 after assigining myrows to query";

    $root = realpath($_SERVER['DOCUMENT_ROOT']);

    print "here 4 after assigning root path";

    foreach($myrows as $row) {

        print "in the loop";

        print "$root/wp-content/themes/weld-wide/images/gates/" . $row->image_path;

        unlink("$root/wp-content/themes/weld-wide/images/gates/" . $row->image_path);

    }

}

The code line print "in the loop"; that is inside the very last foreach isn't printing to screen hence it is not going inside the loop, question is why?

Thanks in advance

Answer 1

You are trying to select rows you just have deleted, this can't work.

$root = realpath($_SERVER['DOCUMENT_ROOT']);
foreach($checkbox as $id) {

    $id = intval($id); //protects from sql injection (assuming your ids are integers)

    //First get the row to delete its image :
    $myrows = $wpdb->get_results("SELECT `image_path` FROM `gate_options` WHERE `id` = $id LIMIT 1");

    print "Removing : $root/wp-content/themes/weld-wide/images/gates/" . $myrows[0]->image_path;
    unlink("$root/wp-content/themes/weld-wide/images/gates/" . $myrows[0]->image_path);

    //Then delete the row :
    $wpdb->query("DELETE FROM `gate_options` WHERE `id` = '$id' LIMIT 1");

}

Answer 2

You either have no rows or have a masked error which is ending the script prematurely.

SQL result:

$wpdb->get_results() returns NULL if there are no results available for debugging use var_dump($myrows) and to avoid passing a NULL to the foreach (which expects an array) use

if ($myrows !== NULL) 
{
    /* foreach in here */
}

Or

if (!empty($myrows))
{
    /* foreach in here */
}

Error reporting:

To check for errors you should add the following at the beginning of your script:

error_reporting(E_ALL);
ini_set('display_errors', true);

Best approach:

if(isset($_POST["delete"]))
{

    $checkbox = $_POST['checkbox'];

    /* this converts every item to an Integer */
    /* which helps sanitize input, and avoid SQL injection attacs */
    $checkbox = array_map('intval', $checkbox);

    /* select all the rows which will be deleted (before deleting them) */
    $myrows = $wpdb->get_results("
        SELECT `image_path`
            FROM `gate_options`
            WHERE `id` IN ( " . implode(', ', $checkbox) . " )
    ");

    /* delete all the rows in one single query */
    $wpdb->query("
        DELETE
            FROM `gate_options`
            WHERE `id` IN ( " . implode(', ', $checkbox) . " )
    ");


    /* remove attachments for the deleted rows */
    $root = realpath($_SERVER['DOCUMENT_ROOT']);
    foreach($myrows as $row)
    {

        print "$root/wp-content/themes/weld-wide/images/gates/" . $row->image_path;
        unlink("$root/wp-content/themes/weld-wide/images/gates/" . $row->image_path);

    }

}