Checking for null radio buttons?

Anon

I have a group of 5 radio buttons for a web rating system. Each of the buttons is named "rating" and has a value from 1 to 5.
None of the buttons are checked by default and I want to ensure that the user has made a selection from the group.

I've tried

if(!(IsSet($rating)){
echo "Please click a button!";
}

and

if(!($rating)){
echo "Please click a button!";
}

without success. How can I correctly test that at least one of the buttons is checked please?

kind regards, Graham

Anon

If the values are numeric (1,2,3,4,5) check the integer value of rating. If the values are strings ("one"->"five"), you can check the string length.

Assuming you're submitting the form using the POST method, and using integer values, your code would look like:

$rate = intval($HTTP_POST_VARS["rating"]);
if($rate < 1) {
// no buttons were checked
}

If you're submitting the form using the "GET" method (not really recommended), and the values are strings, your code could look something like:

if(strlen($HTTP_GET_VARS["rating"]) < 3) {
// no button was checked
}

Have fun---

Anon

But I thought that radio button values only get posted if at least one of the buttons is checked?

I tried making my form post to a temporary page which just contains

<? phpinfo(); ?>

and then I checked out the variables (if any) that are being posted by my form. When none of the "rating" buttons is checked no variable "rating" gets posted. That's why I was originaly using isset and !($rating) to check to see if the variable was being sent.
Any further thoughts please?

mrmufin

First, don't assume that PHP is automatically registering your form values as global. Check the specific $HTTP_POST_VARS or $HTTP_GET_VARS array (depending on how the form is being submitted) for the associated value.

Whenever I use radio buttons in forms, I always pre-select one, if one MUST be selected; that just helps minimize the amount of user data validation that I need to perform on the server.

I seldom use the isset($var) function when processing form data, because all too often simply knowing whether or not a value has been set isn't good enough, but the specific value is more important; this also helps prevent users from pushing invalid form data into my script.

Using your "ratings" radio buttons as an example, and assuming the form is being submitted using the POST method, you could alternatively use a switch statement:

switch(intval($HTTP_POST_VARS["rating"])) {
case 1:
// low rating code goes here
break;
case 2:
break;
case 3:
break;
case 4:
break;
case 5:
// best rating code goes here
break;
default:
// invlaid data
break;
}

This would help assure that a user doesn't do something like edit your form before submitting and stuffing a different value into it.

There's a gazillion and five different ways to validate form data; the trick is arriving at what best accomodates the needs of your application.

Have fun...

planetphp

Try this....

add this function

function error_message($msg) {
echo "<SCRIPT>alert(\"Error: $msg\");history.go(-1)</SCRIPT>";
exit;
}

and then add the name of the form variable to $variable in this code.

This will then give a prompt box with your message.

if(empty($variable)) error_message("Please make a selection!");