001// Copyright 2008 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.corelib.data;
016
017/**
018 * Used with the {@link org.apache.tapestry5.corelib.components.Select} component to control whether an initial blank
019 * option is supplied.  Determines the optionality of the undelrying property from the Select's {@linkplain
020 * org.apache.tapestry5.FieldValidator#isRequired() validate parameter}
021 */
022public enum BlankOption
023{
024    /**
025     * Always include the blank option, even if the underlying property is required.
026     */
027    ALWAYS,
028
029    /**
030     * Never include the blank option, even if the underlying property is optional.
031     */
032    NEVER,
033
034    /**
035     * The default: include the blank option if the underlying property is optional.
036     */
037    AUTO;
038}