MyAwesomePage Validation for has_many fields (in the CMS)

MyAwesomePage.php

<?php

class MyAwesomePage extends Page {

	static $has_many = array(
		"Things" => "AwesomeDataObjects"
	);

	public function getCMSFields() {
		$fields = parent::getCMSFields();
		$fields->addFieldToTab("Root.Content.Stuff", new ComplexTableField(
			$this,
			"Things",
			"AwesomeDataObjects"
		));
		return $fields
	}

	function getCMSValidator(){
		return new MyAwesomePage_Validator("Things");
	}
}

class MyAwesomePage_Validator extends RequiredFields {

	protected $required_many;

	function validate(){

		$x = parent::validate();
		if($this->getErrors()){
			if(Director::is_ajax() && $this->getJavascriptValidationHandler() == 'prototype') {
				foreach($this->getErrors() as $Error){
					FormResponse::status_message($Error["message"],'bad');
				}
			}
		}
		return false;
	}

	function php($data) {

		$obj = $this->form->getRecord();
		$hasMany = Object::combined_static($obj->ClassName, 'has_many', 'DataObject');

		foreach($this->required as $field) {
			if($hasMany && array_key_exists($field, $hasMany)) {
				$this->removeRequiredField($field);
				$this->required_many[] = $field;
			}
		}

		$valid = parent::php($data);

		if($this->required_many) {

			foreach($this->required_many as $fieldName) {

				if($obj->$fieldName()->Count() == 0) {

					$formField = $this->form->Fields()->dataFieldByName($fieldName);

					$this->validationError(
						$fieldName,
						$formField->getCustomValidationMessage() ?
							$formField->getCustomValidationMessage() :
							sprintf(_t('Form.FIELDISREQUIRED', '%s is required').'.', strip_tags('"' . ($formField->Title() ? $formField->Title() : $fieldName) . '"')),
						"required"
					);
					$valid = false;
				}
			}
		}

		return $valid;
	}

}

Check required fields for Pages in SS2 with "has_many" fields.

This is in response to;
http://www.silverstripe.org/customising-the-cms/show/13397
http://www.silverstripe.org/data-model-questions/show/6128#post287065