001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017     
018    package org.apache.commons.beanutils;
019    
020    import org.apache.commons.collections.Predicate;
021    import org.apache.commons.logging.Log;
022    import org.apache.commons.logging.LogFactory;
023    
024    import java.lang.reflect.InvocationTargetException;
025    
026    
027    /**
028     * <p><code>Predicate</code> that evaluates a property value against a specified value.</p>
029     * <p>
030     * An implementation of <code>org.apache.commons.collections.Predicate</code> that evaluates a
031     * property value on the object provided against a specified value and returns <code>true</code>
032     * if equal; <code>false</code> otherwise.
033     * The <code>BeanPropertyValueEqualsPredicate</code> constructor takes two parameters which
034     * determine what property will be evaluated on the target object and what its expected value should
035     * be.
036     * <dl>
037     *    <dt>
038     *       <strong><code>
039     *           <pre>public BeanPropertyValueEqualsPredicate( String propertyName, Object propertyValue )</pre>
040     *       </code></strong>
041     *    </dt>
042     *    <dd>
043     *       Will create a <code>Predicate</code> that will evaluate the target object and return
044     *       <code>true</code> if the property specified by <code>propertyName</code> has a value which
045     *       is equal to the the value specified by <code>propertyValue</code>. Or return
046     *       <code>false</code> otherwise.
047     *    </dd>
048     * </dl>
049     * </p>
050     * <p>
051     * <strong>Note:</strong> Property names can be a simple, nested, indexed, or mapped property as defined by
052     * <code>org.apache.commons.beanutils.PropertyUtils</code>.  If any object in the property path
053     * specified by <code>propertyName</code> is <code>null</code> then the outcome is based on the
054     * value of the <code>ignoreNull</code> attribute.
055     * </p>
056     * <p>
057     * A typical usage might look like:
058     * <code><pre>
059     * // create the closure
060     * BeanPropertyValueEqualsPredicate predicate =
061     *    new BeanPropertyValueEqualsPredicate( "activeEmployee", Boolean.FALSE );
062     *
063     * // filter the Collection
064     * CollectionUtils.filter( peopleCollection, predicate );
065     * </pre></code>
066     * </p>
067     * <p>
068     * This would take a <code>Collection</code> of person objects and filter out any people whose
069     * <code>activeEmployee</code> property is <code>false</code>. Assuming...
070     * <ul>
071     *    <li>
072     *       The top level object in the <code>peeopleCollection</code> is an object which represents a
073     *       person.
074     *    </li>
075     *    <li>
076     *       The person object has a <code>getActiveEmployee()</code> method which returns
077     *       the boolean value for the object's <code>activeEmployee</code> property.
078     *    </li>
079     * </ul>
080     * </p>
081     * <p>
082     * Another typical usage might look like:
083     * <code><pre>
084     * // create the closure
085     * BeanPropertyValueEqualsPredicate predicate =
086     *    new BeanPropertyValueEqualsPredicate( "personId", "456-12-1234" );
087     *
088     * // search the Collection
089     * CollectionUtils.find( peopleCollection, predicate );
090     * </pre><code>
091     * </p>
092     * <p>
093     * This would search a <code>Collection</code> of person objects and return the first object whose
094     * <code>personId</code> property value equals <code>456-12-1234</code>. Assuming...
095     * <ul>
096     *    <li>
097     *       The top level object in the <code>peeopleCollection</code> is an object which represents a
098     *       person.
099     *    </li>
100     *    <li>
101     *       The person object has a <code>getPersonId()</code> method which returns
102     *       the value for the object's <code>personId</code> property.
103     *    </li>
104     * </ul>
105     * </p>
106     *
107     * @author Norm Deane
108     * @see org.apache.commons.beanutils.PropertyUtils
109     * @see org.apache.commons.collections.Predicate
110     */
111    public class BeanPropertyValueEqualsPredicate implements Predicate {
112       
113        /** For logging. */
114        private final Log log = LogFactory.getLog(this.getClass());
115    
116        /**
117         * The name of the property which will be evaluated when this <code>Predicate</code> is executed.
118         */
119        private String propertyName;
120    
121        /**
122         * The value that the property specified by <code>propertyName</code>
123         * will be compared to when this <code>Predicate</code> executes.
124         */
125        private Object propertyValue;
126    
127        /**
128         * <p>Should <code>null</code> objects in the property path be ignored?</p>
129         * <p>
130         * Determines whether <code>null</code> objects in the property path will genenerate an
131         * <code>IllegalArgumentException</code> or not. If set to <code>true</code> then if any objects
132         * in the property path evaluate to <code>null</code> then the
133         * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code> will be logged but
134         * not rethrown and <code>false</code> will be returned.  If set to <code>false</code> then if
135         * any objects in the property path evaluate to <code>null</code> then the
136         * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code> will be logged and
137         * rethrown.
138         * </p>
139         */
140        private boolean ignoreNull;
141    
142        /**
143         * Constructor which takes the name of the property, its expected value to be used in evaluation,
144         * and assumes <code>ignoreNull</code> to be <code>false</code>.
145         *
146         * @param propertyName The name of the property that will be evaluated against the expected value.
147         * @param propertyValue The value to use in object evaluation.
148         * @throws IllegalArgumentException If the property name provided is null or empty.
149         */
150        public BeanPropertyValueEqualsPredicate(String propertyName, Object propertyValue) {
151            this(propertyName, propertyValue, false);
152        }
153    
154        /**
155         * Constructor which takes the name of the property, its expected value
156         * to be used in evaluation, and a boolean which determines whether <code>null</code> objects in
157         * the property path will genenerate an <code>IllegalArgumentException</code> or not.
158         *
159         * @param propertyName The name of the property that will be evaluated against the expected value.
160         * @param propertyValue The value to use in object evaluation.
161         * @param ignoreNull Determines whether <code>null</code> objects in the property path will
162         * genenerate an <code>IllegalArgumentException</code> or not.
163         * @throws IllegalArgumentException If the property name provided is null or empty.
164         */
165        public BeanPropertyValueEqualsPredicate(String propertyName, Object propertyValue, boolean ignoreNull) {
166            super();
167    
168            if ((propertyName != null) && (propertyName.length() > 0)) {
169                this.propertyName = propertyName;
170                this.propertyValue = propertyValue;
171                this.ignoreNull = ignoreNull;
172            } else {
173                throw new IllegalArgumentException("propertyName cannot be null or empty");
174            }
175        }
176    
177        /**
178         * Evaulates the object provided against the criteria specified when this
179         * <code>BeanPropertyValueEqualsPredicate</code> was constructed.  Equality is based on
180         * either reference or logical equality as defined by the property object's equals method. If
181         * any object in the property path leading up to the target property is <code>null</code> then
182         * the outcome will be based on the value of the <code>ignoreNull</code> attribute. By default,
183         * <code>ignoreNull</code> is <code>false</code> and would result in an
184         * <code>IllegalArgumentException</code> if an object in the property path leading up to the
185         * target property is <code>null</code>.
186         *
187         * @param object The object to be evaluated.
188         * @return True if the object provided meets all the criteria for this <code>Predicate</code>;
189         * false otherwise.
190         * @throws IllegalArgumentException If an IllegalAccessException, InvocationTargetException, or
191         * NoSuchMethodException is thrown when trying to access the property specified on the object
192         * provided. Or if an object in the property path provided is <code>null</code> and
193         * <code>ignoreNull</code> is set to <code>false</code>.
194         */
195        public boolean evaluate(Object object) {
196           
197            boolean evaluation = false;
198    
199            try {
200                evaluation = evaluateValue(propertyValue,
201                        PropertyUtils.getProperty(object, propertyName));
202            } catch (IllegalArgumentException e) {
203                final String errorMsg = "Problem during evaluation. Null value encountered in property path...";
204    
205                if (ignoreNull) {
206                    log.warn("WARNING: " + errorMsg + e);
207                } else {
208                    IllegalArgumentException iae = new IllegalArgumentException(errorMsg);
209                    if (!BeanUtils.initCause(iae, e)) {
210                        log.error(errorMsg, e);
211                    }
212                    throw iae;
213                }
214            } catch (IllegalAccessException e) {
215                final String errorMsg = "Unable to access the property provided.";
216                IllegalArgumentException iae = new IllegalArgumentException(errorMsg);
217                if (!BeanUtils.initCause(iae, e)) {
218                    log.error(errorMsg, e);
219                }
220                throw iae;
221            } catch (InvocationTargetException e) {
222                final String errorMsg = "Exception occurred in property's getter";
223                IllegalArgumentException iae = new IllegalArgumentException(errorMsg);
224                if (!BeanUtils.initCause(iae, e)) {
225                    log.error(errorMsg, e);
226                }
227                throw iae;
228            } catch (NoSuchMethodException e) {
229                final String errorMsg = "Property not found.";
230                IllegalArgumentException iae = new IllegalArgumentException(errorMsg);
231                if (!BeanUtils.initCause(iae, e)) {
232                    log.error(errorMsg, e);
233                }
234                throw iae;
235            }
236    
237            return evaluation;
238        }
239    
240        /**
241         * Utility method which evaluates whether the actual property value equals the expected property
242         * value.
243         *
244         * @param expected The expected value.
245         * @param actual The actual value.
246         * @return True if they are equal; false otherwise.
247         */
248        protected boolean evaluateValue(Object expected, Object actual) {
249            return (expected == actual) || ((expected != null) && expected.equals(actual));
250        }
251    
252        /**
253         * Returns the name of the property which will be evaluated when this <code>Predicate</code> is
254         * executed.
255         *
256         * @return The name of the property which will be evaluated when this <code>Predicate</code> is
257         * executed.
258         */
259        public String getPropertyName() {
260            return propertyName;
261        }
262    
263        /**
264         * Returns the value that the property specified by <code>propertyName</code> will be compared to
265         * when this <code>Predicate</code> executes.
266         *
267         * @return The value that the property specified by <code>propertyName</code> will be compared to
268         * when this <code>Predicate</code> executes.
269         */
270        public Object getPropertyValue() {
271            return propertyValue;
272        }
273    
274        /**
275         * Returns the flag which determines whether <code>null</code> objects in the property path will
276         * genenerate an <code>IllegalArgumentException</code> or not. If set to <code>true</code> then
277         * if any objects in the property path evaluate to <code>null</code> then the
278         * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code> will be logged but
279         * not rethrown and <code>false</code> will be returned.  If set to <code>false</code> then if
280         * any objects in the property path evaluate to <code>null</code> then the
281         * <code>IllegalArgumentException</code> throw by <code>PropertyUtils</code> will be logged and
282         * rethrown.
283         *
284         * @return The flag which determines whether <code>null</code> objects in the property path will
285         * genenerate an <code>IllegalArgumentException</code> or not.
286         */
287        public boolean isIgnoreNull() {
288            return ignoreNull;
289        }
290    }