[RESOLVED] Global variable in a form validation function

[gwerner]

I'm validating forms through a series of functions. The only way I can seem to return error messages is through a global variable. I've been reading this is less than ideal. Below is my basic page setup.

I'm not seeing another way around this unless I create a function that also is responsible for displaying the form. I'm hoping to not have to do that. It always seems harder to edit the HTML if it's being echo'd out.

The form posts to itself and calls an external PHP file to handle the validation.

HTML Setup
html...
html...
html...

<form action="<?php $_SERVER['PHP_SELF'] ?>"></form>

// If an error has been found echo the error message above the form
<?php if (isset($error)) { echo "<h2 class=\"alert clear\">There were errors with the information you've entered.</h2>"; } ?>

External PHP Form Validation

// Determines what action to take based on type of form submitted
switch ($action) {
	case 'processForm' :
		processForm();
		break;

default :
	header('Location: index.php');
}

// First set of validation
function checkSet() {
	return isset($_POST['billFirst'], $_POST['billLast'], ...);
}

// Calls the first check and if passes proceeds with the second set
function checkFields() {
	global $error;
	if (checkSet() != FALSE) {
		if (empty($_POST['billFirst']) == TRUE || valName($_POST['billFirst'], 'string') != TRUE) {
		$error['billFirst'] = 'T';
		}
		if (empty($_POST['billLast']) == TRUE || valName($_POST['billLast'], 'string') != TRUE) {
		$error['billLast'] = 'T';
		}
	}
	else {
		$error[] = 'T';
	}
	return (!isset($error));
}

function processForm() {

if (checkFields() != TRUE) {
	return FALSE;
}
else {
	Do a database INSERT, SELECT OR UPDATE etc...
}
}

[NogDog]

The simple solution is to pass the error variable by reference.

[Weedpacket]

Or just initialise $error to be an empty array at the start of the function, and return it at the end of the function.

Then when you use the function, see if what it returns is [man]empty[/man] or not. If it's empty, then there are no errors in it. If it's not empty, then it does have something in it (and you can find out what).

[gwerner]

I think I understand the method you are suggesting NogDog. I definitely understand what Weedpacket is saying.

The thing that still eludes me is how to display the returned value if the function is activated by a POST?

<form action="<?php $_SERVER['PHP_SELF'] ?>">
<input type="hidden" name="action" value="processBilling" />
</form>

The processForm() function is called if POST action processForm is set. This function has an if/else statement which calls the second function checkFields(). This function first calsl to third function checkSet(). checkSet() makes sure all the fields have been set. If TRUE, then CheckFields() validates the inputs. There could be multiple errors, and I want to display them all at once. If processForm() is the last function to execute, then this is where I think the $error variable should return if FALSE.

This is what I have at the top of the form page that makes a general alert statement.
if (isset($error)) { echo 'The alert message'; }

This is what I'm using to highlight the input labels that ere missed or had improper data.
if (isset($error['billFirst'])) { echo 'class=error'; }

But again, not sure how to return, if it was called by a POST? It works if I use the global $error. What am not getting?

Thanks for any additional help.

[NogDog]

You can use a negated empty() instead of an isset().

if(!empty($error)) { echo $error; }

That would be particularly useful with Weedpacket's suggestion. If you went with a passed-by-reference variable and separate boolean return value, it might be something like:

if(!validationFunction($error)) { echo $error; }

(Assumes validationFunction() returns false if there is an error, and $error is passed by reference and contains the error message text)

Another option would be to go object-oriented with perhaps some sort of validation class, saving the last error in a class variable.

class Validate
{
   public static $lastError = '';
   public static function stringLength($str, $min, $max, $name)
   {
      if(strelen($str) < $min)
      {
         $this->lastError = "'$name' must be at least $min characters long.";
         return false;
      }
      elseif(strlen($str) > $max)
      {
         $this->lastError = "'$name' must be no more than $max characters long.";
         return false;
      }
      return true;
   }
}

// usage
if(!validate::stringLength($string, 5, 15, 'Name')) {
   echo Validate::$lastError;
}

[gwerner]

At long last I believe I've got it. Your help has guided the way once again. Thanks guys.