diff --git a/core/model/DataObject.php b/core/model/DataObject.php
index 0b43a66b7..4ad36d799 100644
--- a/core/model/DataObject.php
+++ b/core/model/DataObject.php
@@ -1591,10 +1591,15 @@ class DataObject extends Controller implements DataObjectInterface {
 	 */
 	public static function get_by_id($callerClass, $id) {
 		if(is_numeric($id)) {
-			$tableClasses = ClassInfo::dataClassesFor($callerClass);
-			$baseClass = array_shift($tableClasses);
-			
-			return DataObject::get_one($callerClass,"`$baseClass`.`ID` = $id");
+			if(singleton($callerClass) instanceof DataObject) {
+				$tableClasses = ClassInfo::dataClassesFor($callerClass);
+				$baseClass = array_shift($tableClasses);
+				return DataObject::get_one($callerClass,"`$baseClass`.`ID` = $id");
+				
+			// This simpler code will be used by non-DataObject classes that implement DataObjectInterface
+			} else {
+				return DataObject::get_one($callerClass,"`ID` = $id");
+			}
 		} else {
 			user_error("DataObject::get_by_id passed a non-numeric ID #$id", E_USER_WARNING);
 		}
diff --git a/core/model/DataObjectInterface.php b/core/model/DataObjectInterface.php
index 8b8b4f178..de9a7c172 100755
--- a/core/model/DataObjectInterface.php
+++ b/core/model/DataObjectInterface.php
@@ -44,4 +44,17 @@ interface DataObjectInterface {
 	 */
 	function delete();
 	
+	/**
+	 * Get the named field.
+	 * This function is sometimes called explicitly by the form system, so you need to define it, even if you use the
+	 * default field system.
+	 */
+	function __get($fieldName);
+	
+	/**
+	 * Save content from a form into a field on this data object.
+	 * Since the data comes straight from a form it can't be trusted and will need to be validated / escaped.'
+	 */
+	function setCastedField($fieldName, $val);
+	
 }
\ No newline at end of file
diff --git a/forms/Form.php b/forms/Form.php
index 624353cda..5d006d9e3 100644
--- a/forms/Form.php
+++ b/forms/Form.php
@@ -529,7 +529,7 @@ class Form extends ViewableData {
 	 * Save the contents of this form into the given data object.
 	 * It will make use of setCastedField() to do this.
 	 */
-	function saveInto(DataObject $dataObject) {
+	function saveInto(DataObjectInterface $dataObject) {
 		$dataFields = $this->fields->dataFields();
 		$lastField = null;
 
diff --git a/forms/FormField.php b/forms/FormField.php
index a843c9075..c8ad27f8b 100644
--- a/forms/FormField.php
+++ b/forms/FormField.php
@@ -96,7 +96,7 @@ class FormField extends ViewableData {
 	 * Method to save this form field into the given data object.
 	 * By default, makes use of $this->dataValue()
 	 */
-	function saveInto(DataObject $record) {
+	function saveInto(DataObjectInterface $record) {
 		if($this->name) {
 			$record->setCastedField($this->name, $this->dataValue());
 		}