    001    //$HeadURL: https://svn.wald.intevation.org/svn/deegree/base/branches/2.4_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    }