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