Comparing with another field

In this recipe, we will add a rule that allows us to ensure the contents of two fields are identical. The classic example of this type of validation is where the accuracy of the information we require from the user is vital (for example, a password or an e-mail address). We ensure that they enter it twice, compare both the entries, and display a warning if they are not identical.

Getting ready

Please refer to the first recipe in this chapter for details on how to prepare a QuickForm web form which is the basis of this recipe.

How to do it...

Add the following code to our form definition in validation_form.php just after the field definition:

$mform->addElement('text', 'mytext12', 'Must be equal (1st)');
$mform->addElement('text', 'mytext12_compare', 'Must be equal (2nd)');
$mform->addRule( array('mytext12','mytext12_compare'), 'Must match', 'compare', 'eq', 'server' );

Now we can test this new rule by entering two different values into each text box. The...