    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
    015    package 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     */
    022    public 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    }