001    /*
002     * Copyright 2002-2004 the original author or authors.
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License"); you may not
005     * use this file except in compliance with the License. You may obtain a copy of
006     * the License at
007     *
008     * http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
012     * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
013     * License for the specific language governing permissions and limitations under
014     * the License.
015     */
016    package org.springframework.rules.constraint.property;
017    
018    import org.springframework.binding.PropertyAccessStrategy;
019    import org.springframework.rules.constraint.Constraint;
020    import org.springframework.util.Assert;
021    
022    /**
023     * A constraint that returns the result of a <code>boolean</code>
024     * expression that tests a variable bean property value against a predicate
025     * (constraint). For example: <code>pet.age is required</code>
026     *
027     * @author Keith Donald
028     */
029    public class PropertyValueConstraint extends AbstractPropertyConstraint implements Constraint {
030    
031            private Constraint valueConstraint;
032    
033            /**
034             * Creates a BeanPropertyValueConstraint.
035             *
036             * @param propertyName
037             *            The constrained property.
038             * @param valueConstraint
039             *            The property value constraint (tester).
040             */
041            public PropertyValueConstraint(String propertyName, Constraint valueConstraint) {
042                    super(propertyName);
043                    Assert.notNull(valueConstraint, "valueConstraint is required");
044                    Assert.isTrue(!(valueConstraint instanceof PropertyConstraint),
045                                    "valueConstraint cannot be a PropertyConstraint - it must be a plain constraint that tests property values!");
046                    this.valueConstraint = valueConstraint;
047            }
048    
049            protected boolean test(PropertyAccessStrategy domainObjectAccessStrategy) {
050                    return valueConstraint.test(domainObjectAccessStrategy.getPropertyValue(getPropertyName()));
051            }
052    
053            public Constraint getConstraint() {
054                    return valueConstraint;
055            }
056    
057            public String toString() {
058                    return valueConstraint.toString();
059            }
060    }