Preselecting Multiple Selection Lists
When it comes to prefilling form elements, multiple selection lists are the most difficult ones to implement. This is because in $_GET or $_POST, you have an array of chosen options; so you cannot just compare strings, but you have to search for the specified value in the array. Luckily, PHP offers something suitable in the form of the in_array() function. So, the effort required is not much more than with the other form elements: If the current value is in $_GET/$_POST, print out the selected attribute. Prefilling Multiple Selection Lists (select-multiple.php; excerpt) <select name="multilistname[]" multiple="multiple" size="3"> <option value="php3"<?php if (isset($_POST['multilistname']) && in_array('php3', $_POST['multilistname'])) { echo ' selected="selected"'; } ?>>PHP 3</option> <option value="php4"<?php if (isset($_POST['multilistname']) && in_array('php4', $_POST['multilistname'])) { echo ' selected="selected"'; } ?>>PHP 4</option> <option value="php5"<?php if (isset($_POST['multilistname']) && in_array('php5', $_POST['multilistname'])) { echo ' selected="selected"'; } ?>>PHP 5</option> </select> However, the HTML form must be specially prepared to allow PHP to access the data from the multiple selection list: The value of the name attribute has to end with [], hinting to PHP that it should expect an array of values, not just a string value. Accessing the list data, however, can still be done using $_GET['listname']/$_POST['listname'] and not $_GET['listname[]']/$_POST['listname[]'], as shown in the preceding code. If you want to prefill the list with data from the cookie, you just have to use the well-known file getFormData.inc.php from the previous phrases. It contains two additional functions that return an array instead of a string. Retrieving Form Data from a Cookie (getFormData.inc.php; excerpt) function getFormDataArrayGET($name) { if (isset($_GET[$name])) { return $_GET[$name]; } else { $cookiedata = getCookieData(); if ($cookiedata != null && isset($cookiedata[$name])) { return $cookiedata[$name]; } } return array(); } function getFormDataArrayPOST($name) { if (isset($_POST[$name])) { return $_POST[$name]; } else { $cookiedata = getCookieData(); if ($cookiedata != null && isset($cookiedata[$name])) { return $cookiedata[$name]; } } return array(); } These functions return an array for multiple lists that you can use as you did in select-multiple.php. Prefilling Multiple Selection Lists (select-multiple-cookie.php; excerpt) <?php require_once 'getFormData.inc.php'; ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/ DTD/ xhtml1-transitional.dtd"> <html> <head> <title>Forms</title> </head> <body> <form method="post" action=" <?php echo htmlspecialchars($_SERVER['PHP_SELF']); ?>"> <select name="multilistname[]" multiple="multiple" size="3"> <option value="php3"<?php if (in_array('php3', getFormDataArrayPOST ('multilistname'))) { echo ' selected="selected"'; } ?>>PHP 3</option> <option value="php4"<?php if (in_array('php4', getFormDataArrayPOST ('multilistname'))) { echo ' selected="selected"'; } ?>>PHP 4</option> <option value="php5"<?php if (in_array('php5', getFormDataArrayPOST ('multilistname'))) { echo ' selected="selected"'; } ?>>PHP 5</option> </select><br /> <input type="submit" /> </form> </body> </html> |
$_POST['multilistname'])) {