silverstripe-blog/code/widgets/BlogCategoriesWidget.php

<?php

if(!class_exists("Widget")) {
	return;
}

/**
 * @method Blog Blog()
 */
class BlogCategoriesWidget extends Widget {
	/**
	 * @var string
	 */
	private static $title = 'Categories';

	/**
	 * @var string
	 */
	private static $cmsTitle = 'Blog Categories';

	/**
	 * @var string
	 */
	private static $description = 'Displays a list of blog categories.';

	/**
	 * @var array
	 */
	private static $db = array(
		'Limit' => 'Int',
		'Order' => 'Varchar',
		'Direction' => 'Varchar',
	);

	/**
	 * @var array
	 */
	private static $has_one = array(
		'Blog' => 'Blog',
	);

	/**
	 * {@inheritdoc}
	 */
	public function getCMSFields() {
		$this->beforeUpdateCMSFields(function (FieldList $fields) {
			$fields[] = DropdownField::create(
				'BlogID', _t('BlogCategoriesWidget.Blog', 'Blog'), Blog::get()->map()
			);

			$fields[] = NumericField::create(
				'Limit', _t('BlogCategoriesWidget.Limit.Label', 'Limit'), 0
			)
				->setDescription(_t('BlogCategoriesWidget.Limit.Description', 'Limit the number of categories shown by this widget (set to 0 to show all categories).'))
				->setMaxLength(3);

			$fields[] = DropdownField::create(
				'Order', _t('BlogCategoriesWidget.Sort.Label', 'Sort'), array('Title' => 'Title', 'Created' => 'Created', 'LastUpdated' => 'Updated')
			)
				->setDescription(_t('BlogCategoriesWidget.Sort.Description', 'Change the order of categories shown by this widget.'));

			$fields[] = DropdownField::create(
				'Direction', _t('BlogCategoriesWidget.Direction.Label', 'Direction'), array('ASC' => 'Ascending', 'DESC' => 'Descending')
			)
				->setDescription(_t('BlogCategoriesWidget.Direction.Description', 'Change the direction of ordering of categories shown by this widget.'));
		});

		return parent::getCMSFields();
	}

	/**
	 * @return DataList
	 */
	public function getCategories() {
		$blog = $this->Blog();

		if (!$blog) {
			return array();
		}

		$query = $blog->Categories();

		if ($this->Limit) {
			$query = $query->limit(Convert::raw2sql($this->Limit));
		}

		if ($this->Order && $this->Direction) {
			$query = $query->sort(Convert::raw2sql($this->Order), Convert::raw2sql($this->Direction));
		}

		return $query;
	}
}

class BlogCategoriesWidget_Controller extends Widget_Controller {

}