001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *
010 *        http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 */
019
020package org.apache.isis.core.metamodel.facets.mandatory;
021
022import org.apache.isis.core.metamodel.adapter.ObjectAdapter;
023import org.apache.isis.core.metamodel.facetapi.Facet;
024import org.apache.isis.core.metamodel.facetapi.FacetHolder;
025import org.apache.isis.core.metamodel.facets.MarkerFacet;
026import org.apache.isis.core.metamodel.interactions.ValidatingInteractionAdvisor;
027
028/**
029 * Whether a property or a parameter is mandatory (not optional).
030 * 
031 * <p>
032 * For a mandatory property, the object cannot be saved/updated without the
033 * value being provided. For a mandatory parameter, the action cannot be invoked
034 * without the value being provided.
035 * 
036 * <p>
037 * In the standard Apache Isis Programming Model, specify mandatory by
038 * <i>omitting</i> the <tt>@Optional</tt> annotation.
039 */
040public interface MandatoryFacet extends MarkerFacet, ValidatingInteractionAdvisor {
041
042    /**
043     * Whether this value is required but has not been provided (and is
044     * therefore invalid).
045     * 
046     * <p>
047     * If the value has been provided, <i>or</i> if the property or parameter is
048     * not required, then will return <tt>false</tt>.
049     */
050    boolean isRequiredButNull(ObjectAdapter adapter);
051
052    /**
053     * Indicates that the implementation is overridding the usual semantics, in
054     * other words that the {@link FacetHolder} to which this {@link Facet} is
055     * attached is <i>not</i> mandatory.
056     */
057    public boolean isInvertedSemantics();
058}