Properly optimize the columns to load, when subitems are requested.

git-svn-id: http://svn.code.sf.net/p/itop/code/trunk@3168 a333f486-631f-4898-b8df-5754b55c2be0

webservices/export.php

@@ -147,6 +147,11 @@ if (!empty($sExpression))
 			{
 				throw new CoreException("Invalid field specification $sField: $sAttCode is not a valid attribute for $sClass");
 			}
+			$oAttDef = MetaModel::GetAttributeDef($sClass, $sAttCode);
+			if ($oAttDef instanceof AttributeSubItem)
+			{
+				$aAliasToFields[$sClassAlias][] = $oAttDef->GetParentAttCode();
+			}
 		}
 
 		// Read query parameters