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.progmodel.facets.properties.validate;
021
022import org.apache.isis.core.metamodel.adapter.ObjectAdapter;
023import org.apache.isis.core.metamodel.facetapi.Facet;
024import org.apache.isis.core.metamodel.facets.properties.modify.PropertySetterFacet;
025import org.apache.isis.core.metamodel.facets.properties.modify.PropertySetterFacetAbstract;
026import org.apache.isis.core.metamodel.interactions.ValidatingInteractionAdvisor;
027
028/**
029 * The mechanism by which the proposed value of a property can be validated,
030 * called immediately before {@link PropertySetterFacetAbstract setting the
031 * value}.
032 * 
033 * <p>
034 * In the standard Apache Isis Programming Model, corresponds to invoking the
035 * <tt>validateXxx</tt> method for a property with an accessor of
036 * <tt>getXxx</tt>.
037 * 
038 * @see PropertySetterFacet
039 */
040
041public interface PropertyValidateFacet extends Facet, ValidatingInteractionAdvisor {
042
043    /**
044     * The reason why the proposed value is invalid.
045     * 
046     * <p>
047     * Should return <tt>null</tt> if the value is in fact valid.
048     */
049    public String invalidReason(ObjectAdapter targetObject, ObjectAdapter proposedValue);
050}