In this recipe, we will add a rule that requires a valid number to be entered, without a leading digit, 0. This is useful for validating whole numbers without zero padding.
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.
Add the following code to our form definition in
validation_form.php, just after the field definition:
$mform->addElement('text', 'mytext11', 'No leading zero'); $mform->addRule('mytext11', 'No leading zero', 'nonzero', null, 'client');
Now we can test the rule by adding an invalid sequence of digits with a leading zero: 0123. We see that our validation warning message is displayed ...