Added DataObjectInterface, which other classes can implement to hook into DataObject::get

git-svn-id: svn://svn.silverstripe.com/silverstripe/open/modules/sapphire/trunk@46057 467b73ca-7a2a-4603-9d3b-597d59a354a9

core/model/DataObject.php

@@ -8,7 +8,7 @@
 /**
  * A single database record & abstract class for the data-access-model.
  */
-class DataObject extends Controller {
+class DataObject extends Controller implements DataObjectInterface {
 	/**
 	 * Data stored in this objects database record. An array indexed
 	 * by fieldname.

core/model/DataObjectInterface.php

@@ -0,0 +1,47 @@
+<?php
+
+/** 
+ * DataObjectInterface is an interface that other data systems in your application can implement in order to behave in a manner
+ * similar to DataObject.
+ *
+ * In addition to the methods defined below, the data of the object should be directly accessible as fields.
+ */
+interface DataObjectInterface {
+	/**
+	 * Create a new data object, not yet in the database.  To load an object into the database, a null object should be constructed,
+	 * its fields set, and the write() method called.
+	 */
+	function __construct();
+
+	/**
+	 * Perform a search query on this data source
+	 *
+	 * @param $filter A filter expression of some kind, in SQL format.
+	 * @param $sort A sort expression, in SQL format.
+	 * @param $join A join expression.  May or may not be relevant.
+	 * @param $limit A limit expression, either "(count)", or "(start), (count)"
+	 */
+	function instance_get($filter = "", $sort = "", $join = "", $limit = "", $containerClass = "DataObjectSet");
+
+	/**
+	 * Retrieve a single record from this data source
+	 *
+	 * @param $filter A filter expression of some kind, in SQL format.
+	 * @param $sort A sort expression, in SQL format.
+	 * @param $join A join expression.  May or may not be relevant.
+	 * @param $limit A limit expression, either "(count)", or "(start), (count)"
+	 */
+	function instance_get_one($filter, $sort = "");
+
+	/**
+	 * Write the current object back to the database.  It should know whether this is a new object, in which case this would
+	 * be an insert command, or if this is an existing object queried from the database, in which case thes would be 
+	 */
+	function write();
+	
+	/**
+	 * Remove this object from the database.  Doesn't do anything if this object isn't in the database.
+	 */
+	function delete();
+	
+}