Source Code Cross Referenced for Reference.java in  » Database-ORM » Velosurf » velosurf » validation » Java Source Code / Java DocumentationJava Source Code and Java Documentation

001:        /*
002:         * Copyright 2003 The Apache Software Foundation.
003:         *
004:         * Licensed under the Apache License, Version 2.0 (the "License");
005:         * you may not use this file except in compliance with the License.
006:         * You may obtain a copy of the License at
007:         *
008:         *     http://www.apache.org/licenses/LICENSE-2.0
009:         *
010:         * Unless required by applicable law or agreed to in writing, software
011:         * distributed under the License is distributed on an "AS IS" BASIS,
012:         * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013:         * See the License for the specific language governing permissions and
014:         * limitations under the License.
015:         */
016:
017:        package velosurf.validation;
018:
019:        import java.util.ArrayList;
020:        import java.util.List;
021:        import java.util.Locale;
022:        import java.sql.SQLException;
023:
024:        import velosurf.sql.Database;
025:        import velosurf.sql.PooledPreparedStatement;
026:        import velosurf.util.Logger;
027:
028:        /**
029:         * <p>A foreign key constraint. Syntax is:</p>
030:         *  <pre>
031:         *    &lt;<i>column</i> references="<i>table.foreign-key</i>"&gt;
032:         * </pre>
033:         * <p>Or:</p>
034:         * <pre>
035:         *   &lt;<i>column</i>&gt;
036:         *     &lt;references foreign-key="<i>table.foreign-key</i>" [message="<i>error-message</i>"]/&gt;
037:         *   &lt;/<i>column</i>&gt;
038:         * </pre>
039:         *
040:         * <p>Note: his constraint is not meant to replace an internal SQL "references" clause in the database,
041:         * since it cannot be made sure that complex updates will respect this constraint.</p>
042:         *
043:         *  @author <a href="mailto:claude.brisson@gmail.com">Claude Brisson</a>
044:         */
045:        public class Reference extends FieldConstraint {
046:
047:            /** database */
048:            private Database db = null;
049:            /** table */
050:            private String table = null;
051:            /** column */
052:            private String column = null;
053:
054:            /**
055:             * Constructor.
056:             * @param table the table name
057:             * @param column the column name
058:             */
059:            public Reference(Database db, String table, String column) {
060:                this .db = db;
061:                this .table = table;
062:                this .column = column;
063:                setMessage("field {0}: value '{1}' not found in " + table + "."
064:                        + column);
065:            }
066:
067:            /**
068:             * Validate data against this constraint.
069:             * @param data the data to be validated
070:             * @return true if data respects the specified reference
071:             */
072:            public boolean validate(Object data) {
073:                try {
074:                    if (data == null || data.toString().length() == 0)
075:                        return true;
076:                    List<Object> param = new ArrayList<Object>();
077:                    param.add(data);
078:                    /* TODO this kind of query may vary with dbms...
079:                       - under Oracle, we need to add "from dual"
080:                       - does it return "1" or "true"?
081:                      So, need to add some stuff to DriverInfo.
082:                      For now, tweak the ping query.*/
083:
084:                    String query = db.getDriverInfo().getPingQuery();
085:                    query = query.replace("1", "? in (select distinct "
086:                            + column + " from " + table + ")");
087:                    PooledPreparedStatement stmt = db.prepare(query);
088:                    Object ret = stmt.evaluate(param);
089:                    return ret != null && ret.equals(Boolean.valueOf(true));
090:                } catch (SQLException sqle) {
091:                    Logger
092:                            .warn("reference constraint validation threw an exception: "
093:                                    + sqle.getMessage());
094:                    return false;
095:                }
096:            }
097:
098:            /**
099:             * return a string representation for this constraint.
100:             * @return string
101:             */
102:            public String toString() {
103:                return "references " + table + "." + column;
104:            }
105:
106:        }