001 //$HeadURL: svn+ssh://jwilden@svn.wald.intevation.org/deegree/base/branches/2.5_testing/src/org/deegree/io/datastore/schema/TableRelation.java $
002 /*----------------------------------------------------------------------------
003 This file is part of deegree, http://deegree.org/
004 Copyright (C) 2001-2009 by:
005 Department of Geography, University of Bonn
006 and
007 lat/lon GmbH
008
009 This library is free software; you can redistribute it and/or modify it under
010 the terms of the GNU Lesser General Public License as published by the Free
011 Software Foundation; either version 2.1 of the License, or (at your option)
012 any later version.
013 This library is distributed in the hope that it will be useful, but WITHOUT
014 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
015 FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
016 details.
017 You should have received a copy of the GNU Lesser General Public License
018 along with this library; if not, write to the Free Software Foundation, Inc.,
019 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
020
021 Contact information:
022
023 lat/lon GmbH
024 Aennchenstr. 19, 53177 Bonn
025 Germany
026 http://lat-lon.de/
027
028 Department of Geography, University of Bonn
029 Prof. Dr. Klaus Greve
030 Postfach 1147, 53001 Bonn
031 Germany
032 http://www.geographie.uni-bonn.de/deegree/
033
034 e-mail: info@deegree.org
035 ----------------------------------------------------------------------------*/
036 package org.deegree.io.datastore.schema;
037
038 import org.deegree.io.datastore.DatastoreTransaction;
039 import org.deegree.io.datastore.idgenerator.IdGenerationException;
040 import org.deegree.io.datastore.idgenerator.IdGenerator;
041 import org.deegree.io.datastore.schema.content.MappingField;
042
043 /**
044 * Describes a relation (join condition) between two database tables.
045 *
046 * @author <a href="mailto:schneider@lat-lon.de">Markus Schneider </a>
047 * @author last edited by: $Author: mschneider $
048 *
049 * @version $Revision: 18195 $, $Date: 2009-06-18 17:55:39 +0200 (Do, 18 Jun 2009) $
050 */
051 public class TableRelation {
052
053 /**
054 * Used to represent the foreign key position.
055 */
056 public static enum FK_INFO {
057
058 /**
059 * No foreign key information available (sufficient for read access).
060 */
061 noFKInfo,
062
063 /**
064 * Foreign stored in 'To'-table, primary key in 'From'-table.
065 */
066 fkIsToField,
067
068 /**
069 * Foreign stored in 'From'-table, primary key in 'To'-table.
070 */
071 fkIsFromField
072 }
073
074 private MappingField[] fromFields;
075
076 private MappingField[] toFields;
077
078 private FK_INFO fkInfo;
079
080 private IdGenerator idGenerator;
081
082 /**
083 * Initializes a newly created <code>TableRelation</code> instance with the given
084 * parameters.
085 *
086 * @param fromFields
087 * @param toFields
088 * @param fkInfo
089 * @param idGenerator
090 */
091 public TableRelation( MappingField[] fromFields, MappingField[] toFields, FK_INFO fkInfo,
092 IdGenerator idGenerator ) {
093 if ( fromFields.length < 1 ) {
094 throw new IllegalArgumentException(
095 "A relation between two tables must have at least one 'from' field." );
096 }
097 if ( toFields.length < 1 ) {
098 throw new IllegalArgumentException(
099 "A relation between two tables must have at least one 'to' field." );
100 }
101 if ( fromFields.length != toFields.length ) {
102 throw new IllegalArgumentException(
103 "A relation between two tables must have the same number of 'from' and 'to' fields." );
104 }
105 this.fromFields = fromFields;
106 this.toFields = toFields;
107 this.fkInfo = fkInfo;
108 this.idGenerator = idGenerator;
109 }
110
111 /**
112 * Returns the name of the table where the relation starts ('From'-table).
113 *
114 * @return the name of the table where the relation starts ('From'-table)
115 */
116 public String getFromTable() {
117 return fromFields[0].getTable();
118 }
119
120 /**
121 * Returns the name of the table where the relation ends ('To'-table).
122 *
123 * @return the name of the table where the relation ends ('To'-table)
124 */
125 public String getToTable() {
126 return toFields[0].getTable();
127 }
128
129 /**
130 * Returns the {@link MappingField}s that constitute the key in the 'From'-table.
131 *
132 * @return the MappingFields that constitute the key in the 'From'-table
133 */
134 public MappingField [] getFromFields () {
135 return this.fromFields;
136 }
137
138 /**
139 * Returns the {@link MappingField}s that constitute the key in the 'To'-table.
140 *
141 * @return the MappingFields that constitute the key in the 'To'-table
142 */
143 public MappingField [] getToFields () {
144 return this.toFields;
145 }
146
147 /**
148 * Returns the foreign key position.
149 *
150 * @return the foreign key position
151 */
152 public FK_INFO getFKInfo () {
153 return this.fkInfo;
154 }
155
156 /**
157 * Returns whether the foreign key is stored in the 'From'-table.
158 *
159 * @return true, if foreign key information is available and foreign key is in 'From'-table,
160 * false otherwise
161 */
162 public boolean isFromFK() {
163 boolean isFromFK = false;
164 switch (this.fkInfo) {
165 case fkIsFromField: {
166 isFromFK = true;
167 break;
168 }
169 case fkIsToField: {
170 isFromFK = false;
171 break;
172 }
173 default: {
174 throw new RuntimeException( "No foreign key information available for relation: "
175 + this );
176 }
177 }
178 return isFromFK;
179 }
180
181
182 /**
183 * Returns the {@link IdGenerator} instance that may be used to generate new primary keys.
184 *
185 * @return IdGenerator instance that may be used to generate new primary keys
186 */
187 public IdGenerator getIdGenerator () {
188 return this.idGenerator;
189 }
190
191 /**
192 * Returns a new primary key generated by the associated {@link IdGenerator}.
193 *
194 * @param ta
195 * @return a new primary key
196 * @throws IdGenerationException
197 */
198 public Object getNewPK( DatastoreTransaction ta ) throws IdGenerationException {
199 return this.idGenerator.getNewId( ta );
200 }
201
202 @Override
203 public String toString() {
204 StringBuffer sb = new StringBuffer();
205 sb.append( getFromTable() );
206 if (this.fkInfo == FK_INFO.fkIsFromField) {
207 sb.append(" (fk) ");
208 }
209 sb.append( " -> " );
210 sb.append( getToTable() );
211 if (this.fkInfo == FK_INFO.fkIsToField) {
212 sb.append(" (fk) ");
213 }
214 sb.append( " (" );
215 for (int i = 0; i < fromFields.length; i++) {
216 sb.append( fromFields[i] );
217 sb.append( "=" );
218 sb.append( toFields[i] );
219 if ( i != fromFields.length - 1 ) {
220 sb.append( " AND " );
221 }
222 }
223 sb.append( ")" );
224 return sb.toString();
225 }
226 }