1 /**
2 * This file Copyright (c) 2008-2010 Magnolia International
3 * Ltd. (http://www.magnolia-cms.com). All rights reserved.
4 *
5 *
6 * This file is dual-licensed under both the Magnolia
7 * Network Agreement and the GNU General Public License.
8 * You may elect to use one or the other of these licenses.
9 *
10 * This file is distributed in the hope that it will be
11 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12 * implied warranty of MERCHANTABILITY or FITNESS FOR A
13 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14 * Redistribution, except as permitted by whichever of the GPL
15 * or MNA you select, is prohibited.
16 *
17 * 1. For the GPL license (GPL), you can redistribute and/or
18 * modify this file under the terms of the GNU General
19 * Public License, Version 3, as published by the Free Software
20 * Foundation. You should have received a copy of the GNU
21 * General Public License, Version 3 along with this program;
22 * if not, write to the Free Software Foundation, Inc., 51
23 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24 *
25 * 2. For the Magnolia Network Agreement (MNA), this file
26 * and the accompanying materials are made available under the
27 * terms of the MNA which accompanies this distribution, and
28 * is available at http://www.magnolia-cms.com/mna.html
29 *
30 * Any modifications to this file must keep this entire header
31 * intact.
32 *
33 */
34 package info.magnolia.module.rssaggregator.util;
35
36 import info.magnolia.cms.core.Content;
37 import info.magnolia.cms.core.ItemType;
38 import info.magnolia.cms.core.search.Query;
39 import info.magnolia.cms.util.QueryUtil;
40 import org.slf4j.Logger;
41 import org.slf4j.LoggerFactory;
42
43 import javax.jcr.RepositoryException;
44 import java.util.ArrayList;
45 import java.util.Collection;
46 import static java.util.Collections.*;
47 import java.util.List;
48
49 /**
50 * Convenience class to simplify use of Magnolia queries and the mapping of their results to types. <p/> Note that all
51 * queries performed by this class are logged at DEBUG level for convenient debugging when necessary.
52 *
53 * @author Rob van der Linden Vooren
54 * @see ContentMapper
55 */
56 public class MagnoliaTemplate implements MagnoliaQueryOperations {
57
58 /** Logger for this instance. */
59 protected Logger logger = LoggerFactory.getLogger(getClass());
60
61 /** {@inheritDoc} */
62 public <T> List<T> queryForList(String repository, String query, String language, ItemType type, ContentMapper<T> mapper) {
63 return query(repository, query, language, type, mapper);
64 }
65
66 /** {@inheritDoc} */
67 public <T> T queryForObject(String repository, String query, String language, ItemType type, ContentMapper<T> mapper) {
68 List<T> results = query(repository, query, language, type, mapper);
69 return singleResult(results);
70 }
71
72 /** {@inheritDoc} */
73 public <T> List<T> xpathQueryForList(String repository, String query, ItemType type, ContentMapper<T> mapper) throws DataAccessException {
74 return queryForList(repository, query, Query.XPATH, type, mapper);
75 }
76
77 /** {@inheritDoc} */
78 public <T> T xpathQueryForObject(String repository, String query, ItemType type, ContentMapper<T> mapper) throws DataAccessException {
79 return queryForObject(repository, query, Query.XPATH, type, mapper);
80 }
81
82 /** {@inheritDoc} */
83 public Content xpathQueryForContent(String repository, String query, ItemType type) throws DataAccessException {
84 return queryForObject(repository, query, Query.XPATH, type, new ContentMapper<Content>() {
85 public Content map(Content content) throws RepositoryException {
86 return content;
87 }
88 });
89 }
90
91 // Helper methods
92
93 protected <T> List<T> query(String repository, String query, String language, ItemType type, ContentMapper<T> mapper) throws DataAccessException {
94 Collection<Content> contents = queryInternal(repository, query, language, type);
95 if (contents.isEmpty()) {
96 return emptyList();
97 }
98 List<T> result = new ArrayList<T>(contents.size());
99 for (Content content : contents) {
100 try {
101 result.add(mapper.map(content));
102 } catch (RepositoryException re) {
103 throw new DataAccessException(String.format("Failed to map content '%s' using mapper '%s'", content, mapper.getClass()));
104 }
105 }
106 return result;
107 }
108
109 /**
110 * Performs the actual query execution. Purposely delegates to {@link QueryUtil#exceptionThrowingQuery(String,
111 * String, String, String) QueryUtil.exceptionThrowingQuery(..)} in order to provide flexibility with regards to
112 * error handling, by translating any {@link RepositoryException} into an unchecked {@link DataAccessException}.
113 * This allows for optional exception handling and logging, making it a better alternative then using {@link
114 * QueryUtil#query(String, String) QueryUtil.query(..)} direcltly, which logs the error and then directly swallows
115 * the {@link RepositoryException exception}. Execute a query for a result list of type T, for the given query.
116 *
117 * @param repository the repository to execute query against
118 * @param query query to execute
119 * @param language query language (either {@value Query#XPATH} or {@value Query#SQL}).
120 * @param type the type of the item to query for
121 * @return the result object of the required type, or {@code null} in case of a {@code null} query
122 * @throws DataAccessException if there is any problem executing the query
123 */
124 protected <T> Collection<T> queryInternal(String repository, String query, String language, ItemType type) {
125 try {
126 return doExceptionThrowingQuery(repository, query, language, type);
127 } catch (RepositoryException re) {
128 throw new DataAccessException("A repository exception occurred", re);
129 }
130 }
131
132 @SuppressWarnings("unchecked")
133 protected <T> Collection<T> doExceptionThrowingQuery(String repository, String query, String language, ItemType type) throws RepositoryException {
134 logger.debug("Executing {} query for '{}' in repository '{}': \"{}\"", new Object[] {language,
135 type.getSystemName(), repository, query}
136 );
137 Collection<T> results = (Collection<T>) QueryUtil.exceptionThrowingQuery(repository, query, language, type.getSystemName());
138 logger.debug("Query returned %s result(s)", (results == null) ? null : results.size());
139 return results;
140 }
141
142 /**
143 * Return a single result object from the given collection or {@code null} if the collection is empty or null.
144 *
145 * @param results the result collection (may be {@code null})
146 * @return the single result object, or {@code null} when no result
147 * @throws IncorrectResultSizeDataAccessException
148 * if collection contains more than one element
149 */
150 protected static <T> T singleResult(Collection<T> results) throws IncorrectResultSizeDataAccessException {
151 int size = (results == null ? 0 : results.size());
152 if (size == 0) {
153 return null;
154 }
155 if (results.size() > 1) {
156 throw new IncorrectResultSizeDataAccessException(1, size);
157 }
158 return results.iterator().next();
159 }
160
161 }