silverstripe-framework/core/model/DataObjectDecorator.php

<?php

/**
 * @package sapphire
 * @subpackage core
 */


/**
 * Plug-ins for additional functionality in your DataObjects
 *
 * DataObject decorators add extra functionality to your data objects.
 */
abstract class DataObjectDecorator extends Extension {

	/**
	 * Load the extra database fields defined in extraDBFields.
	 */
	function loadExtraDBFields() {
		$fields = $this->extraDBFields();
		$className = $this->owner->class;

		if($fields) {
			foreach($fields as $relationType => $fields) {
				if(in_array($relationType, array('db', 'has_one', 'indexes',
																				 'defaults', 'many_many',
																				 'belongs_many_many',
																				 'many_many_extraFields'))) {
					eval("$className::\$$relationType = array_merge((array){$className}::\$$relationType, (array)\$fields);");
				}
			}
		}
	}


	/**
	 * Edit the given query object to support queries for this extension
	 *
	 * @param SQLQuery $query Query to augment.
	 */
	function augmentSQL(SQLQuery &$query) {
	}


	/**
	 * Update the database schema as required by this extension.
	 */
	function augmentDatabase() {
	}


	/**
	 * Define extra database fields
	 *
	 * Return a map where the keys are db, has_one, etc, and the values are
	 * additional fields/relations to be defined.
	 *
	 * @return array Returns a map where the keys are db, has_one, etc, and
	 *               the values are additional fields/relations to be defined.
	 */
	function extraDBFields() {
		return array();
	}


	/**
	 * This function is used to provide modifications to the form in the CMS
	 * by the decorator.
	 * By default, no changes are made - if you want you can overload this
	 * function.
	 *
	 * @param FieldSet $fields The FieldSet to modify.
	 */
	function updateCMSFields(FieldSet &$fields) {
	}
}

?>