Hi, I have added three fields in a page named, FanchisePage. Pretty straight forward.

$fields->addFieldToTab('Root.Content.Main', new TextField('Headline'), 'Content');
$fields->addFieldToTab('Root.Content.Main', new TextField('Phone'), 'Content');
$fields->addFieldToTab('Root.Content.Main', new EmailField('Email'), 'Content');

what I would like to know is, how may I validate this form, when user fill in value in the back end cms area? Let's say, I need make Headline and Email as mandatory field.

Thanks!

I am absolute beginner with Silverstripe.... and i also have this question
How it is possible to use a validator for a field add with

$fields->addFieldToTab('Root.Content.Main', new TextField('Author'), 'Content');

Thank you

As i know in CMSMain validators are supportted from SS 2.4.0 alpha1 by defining getCMSValidator() function in Page object.

In prior versions you can patch CMSMain->getEditForm() function and change Form creation
from:
$form = new Form($this, "EditForm", $fields, $actions);
to:
$validator = ($record->hasMethod('getCMSValidator')) ? $record->getCMSValidator() : null;
$form = new Form($this, "EditForm", $fields, $actions, $validator);