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Basic usage of validators

Having defined validation in this way provides the foundation for Zend_Validate_Interface, which defines two methods, isValid() and getMessages(). The isValid() method performs validation upon the provided value, returning TRUE if and only if the value passes against the validation criteria.

If isValid() returns FALSE, the getMessages() returns an array of messages explaining the reason(s) for validation failure. The array keys are short strings that identify the reasons for validation failure, and the array values are the corresponding human-readable string messages. The keys and values are class-dependent; each validation class defines its own set of validation failure messages and the unique keys that identify them. Each class also has a const definition that matches each identifier for a validation failure cause.


The getMessages() methods return validation failure information only for the most recent isValid() call. Each call to isValid() clears any messages and errors caused by a previous isValid() call, because it's likely that each call to isValid() is made for a different input value.

The following example illustrates validation of an e-mail address:

= new Zend_Validate_EmailAddress();

if (
$validator->isValid($email)) {
// email appears to be valid
} else {
// email is invalid; print the reasons
foreach ($validator->getMessages() as $messageId => $message) {
"Validation failure '$messageId': $message\n";

Zend Framework