PHP Feedback form Checkbox error - php

Question

Ok here is a shortened version of the php for my contact form, (the checkboxes are not being sent through correctly)
<?php
//please fill this in at least!
$myemail = "";
$title = "Feedback Form";
if(isset($_POST['submit'])) { //form has been submitted
//set variables with filters
$cont_name = filter_var($_POST['cont_name'], FILTER_SANITIZE_STRING);
$email = filter_var($_POST['cont_email'], FILTER_SANITIZE_STRING);
$phone = filter_var($_POST['cont_phone'], FILTER_SANITIZE_STRING);
$first_time = filter_var($_POST['first_time'], FILTER_SANITIZE_STRING);
$hear_about = filter_var($_POST['hear_about'], FILTER_SANITIZE_STRING);
function valid_email($str){
return ( ! preg_match("/^([a-z0-9\+_\-]+)(\.[a-z0-9\+_\-]+)*#([a-z0-9\-]+\.)+[a-z]{2,6}$/ix", $str)) ? FALSE : TRUE;}
$errors = 0; //by default there are no errors
$trimcont_name = trim($cont_name);
if(empty($trimcont_name)){
//the name field is empty
$errors = 1; //tips off the error messages below
$errorcont_name = "The name field is empty"; //this error is displayed next to the label
}
if(!valid_email($email)) {
//email is invalid or empty
$errors = 1;
$erroremail = "The email address was not valid";
}
$trimphone = trim($phone);
if(empty($trimphone)){
//the phone field is empty
$errors = 1;
$errorphone = "The phone field is empty";
}
$trimfirst_time = trim($first_time);
if(empty($trimfirst_time)){
//the first_time field is empty
$errors = 1;
$errorfirst_time = "This field is empty";
}
$trimhear_about = trim($hear_about);
if(empty($trimhear_about)){
//the hear_about field is empty
$errors = 1;
$errorhear_about = "This field is empty";
}
if($spam != "") {
//spam was filled in
$errors = 1;
$errorspam = "The Spam box was filled in";
}
if($errors == 0) {
$sendto = $myemail;
$message = <<<DATA
DETAILS
Name: $cont_name
Email: $email
Phone: $phone
Was this the first time you have been to us?
$first_time
How did you hear about us?
$hear_about
DATA;
$headers = 'From: ' . $name . '<' . $email . '>';
if(mail($sendto, $title, $message, $headers)) {
//this is where it sends, using the php mail function
$success = true;
//set all the variables to blank to prevent re-submitting.
$cont_name = "";
$email = "";
$phone = "";
$hear_about = "";
$first_time = "";
} else {
$success = false;
}
} else {
$success = false;
}
}
?>
And the area not functioning correctly is
<fieldset>
<legend>How did you hear about us? <span class="phpformerror"><?php echo $errorhear_about; ?></span></legend>
<div><input type="checkbox" name="hear_about[]" value="Web" /> Web</div>
<div><input type="checkbox" name="hear_about[]" value="Newspaper" /> Newspaper</div>
<div><input type="checkbox" name="hear_about[]" value="Radio" /> Radio</div>
<div><input type="checkbox" name="hear_about[]" value="Driving" /> Driving Past</div>
<div><input type="checkbox" name="hear_about[]" value="Referal" /> Referal</div>
<div><input type="checkbox" name="hear_about[]" value="Other" /> Other</div>
</fieldset>
At the moment it will only come through displaying one of the variables if multiple variables are selected.

Answer 1

hear_about is an array and filter_var() does not handle arrays correctly. Instead use filter_var_array():
$hear_about = filter_var_array($_POST['hear_about'], FILTER_SANITIZE_STRING);
Remember that $hear_about is an array, and must be treated like one throughout your code (e.g. just using $hear_about won't work, it needs to be $hear_about[0], $hear_about[1], etc).
So for example in your trim line you would need something like:
foreach($hear_about as $key => $value) {
$trimhear_about[$key] = trim($value);
if(empty($trimhear_about[$key])){
//the hear_about field is empty
$errors = 1;
$errorhear_about[$key] = "This field is empty";
}
}
This will preserve the benefits of dealing with an array.

Answer 2

$_POST['hear_about'] is an array of values. You are handling it as a simple string!
I think you can solve simply replacing the line:
$hear_about = filter_var($_POST['hear_about'], FILTER_SANITIZE_STRING);
With:
$hear_about = filter_var(implode(', ', $_POST['hear_about']), FILTER_SANITIZE_STRING);
The implode function (doc) "transform" an array to a string by concatenating the array values with the given glue. So you can just concatenate selected "How did you hear about us?" options with a comma and then use the resulting string as the other data.