001// Copyright 2006 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.services;
016
017/**
018 * Represents a previously stored change to a persistent field, within the context of a particular page of the
019 * application.
020 */
021public interface PersistentFieldChange
022{
023    /**
024     * Returns the nested id of the component, or the empty string for the page's root component.
025     */
026    String getComponentId();
027
028    /**
029     * Returns the name of the field for which a change was recorded.
030     */
031    String getFieldName();
032
033    /**
034     * Returns the new value for the field (which may be null).
035     */
036    Object getValue();
037}