cakephp中的javascript验证表示不需要的字段无效

I have a form, one of the inputs of which is:

echo $this->Form->input('email', array('class'=>'formInputRegular halfTd notRequired', 'id'=>'email', 'default'=>'Email'));

The email field of this particular model isn't required. But when I try to submit the form with that input empty the automatic javascript validation appears asking me to enter something.

There is no rule in the model for this field. It's not required in the database. It may once have been (I don't think so) and I've changed it, but I've since re-baked the code for this particular model/controller so that shouldn't be a problem.

Any one any ideas on why the auto javascript validation is kicking in?

It seems to me that it is caused by HTML 5 required attribute. This is a new feature since CakePHP 2.3. Refer to http://book.cakephp.org/2.0/en/core-libraries/helpers/form.html#html5-required

You can turn this off by adding

'novalidate' => true

to the form.