001 //$HeadURL: svn+ssh://rbezema@svn.wald.intevation.org/deegree/base/branches/2.2_testing/src/org/deegree/io/datastore/schema/TableRelation.java $
002 /*---------------- FILE HEADER ------------------------------------------
003
004 This file is part of deegree.
005 Copyright (C) 2001-2008 by:
006 EXSE, Department of Geography, University of Bonn
007 http://www.giub.uni-bonn.de/deegree/
008 lat/lon GmbH
009 http://www.lat-lon.de
010
011 This library is free software; you can redistribute it and/or
012 modify it under the terms of the GNU Lesser General Public
013 License as published by the Free Software Foundation; either
014 version 2.1 of the License, or (at your option) any later version.
015
016 This library is distributed in the hope that it will be useful,
017 but WITHOUT ANY WARRANTY; without even the implied warranty of
018 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
019 Lesser General Public License for more details.
020
021 You should have received a copy of the GNU Lesser General Public
022 License along with this library; if not, write to the Free Software
023 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
024
025 Contact:
026
027 Andreas Poth
028 lat/lon GmbH
029 Aennchenstraße 19
030 53177 Bonn
031 Germany
032 E-Mail: poth@lat-lon.de
033
034 Prof. Dr. Klaus Greve
035 Department of Geography
036 University of Bonn
037 Meckenheimer Allee 166
038 53115 Bonn
039 Germany
040 E-Mail: greve@giub.uni-bonn.de
041
042 ---------------------------------------------------------------------------*/
043 package org.deegree.io.datastore.schema;
044
045 import org.deegree.io.datastore.DatastoreTransaction;
046 import org.deegree.io.datastore.idgenerator.IdGenerationException;
047 import org.deegree.io.datastore.idgenerator.IdGenerator;
048 import org.deegree.io.datastore.schema.content.MappingField;
049
050 /**
051 * Describes a relation (join condition) between two database tables.
052 *
053 * @author <a href="mailto:schneider@lat-lon.de">Markus Schneider </a>
054 * @author last edited by: $Author: apoth $
055 *
056 * @version $Revision: 9342 $, $Date: 2007-12-27 13:32:57 +0100 (Do, 27 Dez 2007) $
057 */
058 public class TableRelation {
059
060 /**
061 * Used to represent the foreign key position.
062 */
063 public static enum FK_INFO {
064
065 /**
066 * No foreign key information available (sufficient for read access).
067 */
068 noFKInfo,
069
070 /**
071 * Foreign stored in 'To'-table, primary key in 'From'-table.
072 */
073 fkIsToField,
074
075 /**
076 * Foreign stored in 'From'-table, primary key in 'To'-table.
077 */
078 fkIsFromField
079 }
080
081 private MappingField[] fromFields;
082
083 private MappingField[] toFields;
084
085 private FK_INFO fkInfo;
086
087 private IdGenerator idGenerator;
088
089 /**
090 * Initializes a newly created <code>TableRelation</code> instance with the given
091 * parameters.
092 *
093 * @param fromFields
094 * @param toFields
095 * @param fkInfo
096 * @param idGenerator
097 */
098 public TableRelation( MappingField[] fromFields, MappingField[] toFields, FK_INFO fkInfo,
099 IdGenerator idGenerator ) {
100 if ( fromFields.length < 1 ) {
101 throw new IllegalArgumentException(
102 "A relation between two tables must have at least one 'from' field." );
103 }
104 if ( toFields.length < 1 ) {
105 throw new IllegalArgumentException(
106 "A relation between two tables must have at least one 'to' field." );
107 }
108 if ( fromFields.length != toFields.length ) {
109 throw new IllegalArgumentException(
110 "A relation between two tables must have the same number of 'from' and 'to' fields." );
111 }
112 this.fromFields = fromFields;
113 this.toFields = toFields;
114 this.fkInfo = fkInfo;
115 this.idGenerator = idGenerator;
116 }
117
118 /**
119 * Returns the name of the table where the relation starts ('From'-table).
120 *
121 * @return the name of the table where the relation starts ('From'-table)
122 */
123 public String getFromTable() {
124 return fromFields[0].getTable();
125 }
126
127 /**
128 * Returns the name of the table where the relation ends ('To'-table).
129 *
130 * @return the name of the table where the relation ends ('To'-table)
131 */
132 public String getToTable() {
133 return toFields[0].getTable();
134 }
135
136 /**
137 * Returns the {@link MappingField}s that constitute the key in the 'From'-table.
138 *
139 * @return the MappingFields that constitute the key in the 'From'-table
140 */
141 public MappingField [] getFromFields () {
142 return this.fromFields;
143 }
144
145 /**
146 * Returns the {@link MappingField}s that constitute the key in the 'To'-table.
147 *
148 * @return the MappingFields that constitute the key in the 'To'-table
149 */
150 public MappingField [] getToFields () {
151 return this.toFields;
152 }
153
154 /**
155 * Returns the foreign key position.
156 *
157 * @return the foreign key position
158 */
159 public FK_INFO getFKInfo () {
160 return this.fkInfo;
161 }
162
163 /**
164 * Returns whether the foreign key is stored in the 'From'-table.
165 *
166 * @return true, if foreign key information is available and foreign key is in 'From'-table,
167 * false otherwise
168 */
169 public boolean isFromFK() {
170 boolean isFromFK = false;
171 switch (this.fkInfo) {
172 case fkIsFromField: {
173 isFromFK = true;
174 break;
175 }
176 case fkIsToField: {
177 isFromFK = false;
178 break;
179 }
180 default: {
181 throw new RuntimeException( "No foreign key information available for relation: "
182 + this );
183 }
184 }
185 return isFromFK;
186 }
187
188
189 /**
190 * Returns the {@link IdGenerator} instance that may be used to generate new primary keys.
191 *
192 * @return IdGenerator instance that may be used to generate new primary keys
193 */
194 public IdGenerator getIdGenerator () {
195 return this.idGenerator;
196 }
197
198 /**
199 * Returns a new primary key generated by the associated {@link IdGenerator}.
200 *
201 * @param ta
202 * @return a new primary key
203 * @throws IdGenerationException
204 */
205 public Object getNewPK( DatastoreTransaction ta ) throws IdGenerationException {
206 return this.idGenerator.getNewId( ta );
207 }
208
209 @Override
210 public String toString() {
211 StringBuffer sb = new StringBuffer();
212 sb.append( getFromTable() );
213 if (this.fkInfo == FK_INFO.fkIsFromField) {
214 sb.append(" (fk) ");
215 }
216 sb.append( " -> " );
217 sb.append( getToTable() );
218 if (this.fkInfo == FK_INFO.fkIsToField) {
219 sb.append(" (fk) ");
220 }
221 sb.append( " (" );
222 for (int i = 0; i < fromFields.length; i++) {
223 sb.append( fromFields[i] );
224 sb.append( "=" );
225 sb.append( toFields[i] );
226 if ( i != fromFields.length - 1 ) {
227 sb.append( " AND " );
228 }
229 }
230 sb.append( ")" );
231 return sb.toString();
232 }
233 }