package org.apache.torque.oid;
/*
* Copyright 2001-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License")
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.math.BigDecimal;
import java.sql.Connection;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.torque.adapter.DB;
import com.workingdogs.village.QueryDataSet;
import com.workingdogs.village.Record;
import com.workingdogs.village.Value;
/**
* This generator works with databases that have an sql syntax for
* getting an id prior to inserting a row into the database.
*
* @author <a href="mailto:jmcnally@collab.net">John D. McNally</a>
* @version $Id: SequenceIdGenerator.java,v 1.10.2.2 2004/05/20 04:36:07 seade Exp $
*/
public class SequenceIdGenerator implements IdGenerator
{
/** The log. */
private static Log log = LogFactory.getLog(SequenceIdGenerator.class);
/** the adapter that knows the correct sql syntax */
private DB dbAdapter;
/**
* Creates an IdGenerator which will work with the specified database.
*
* @param adapter the adapter that knows the correct sql syntax.
*/
public SequenceIdGenerator(DB adapter)
{
dbAdapter = adapter;
}
/**
* Retrieves an id as an int.
*
* @param connection A Connection.
* @param keyInfo an Object that contains additional info.
* @return An int with the value for the id.
* @exception Exception Database error.
*/
public int getIdAsInt(Connection connection, Object keyInfo)
throws Exception
{
return getIdAsVillageValue(connection, keyInfo).asInt();
}
/**
* Retrieves an id as an long.
*
* @param connection A Connection.
* @param keyInfo an Object that contains additional info.
* @return A long with the value for the id.
* @exception Exception Database error.
*/
public long getIdAsLong(Connection connection, Object keyInfo)
throws Exception
{
return getIdAsVillageValue(connection, keyInfo).asLong();
}
/**
* Retrieves an id as a BigDecimal.
*
* @param connection A Connection.
* @param keyInfo an Object that contains additional info.
* @return A BigDecimal id
* @exception Exception Database error.
*/
public BigDecimal getIdAsBigDecimal(Connection connection, Object keyInfo)
throws Exception
{
return getIdAsVillageValue(connection, keyInfo).asBigDecimal();
}
/**
* Retrieves an id as an String.
*
* @param connection A Connection.
* @param keyInfo an Object that contains additional info.
* @return A String id
* @exception Exception Database error.
*/
public String getIdAsString(Connection connection, Object keyInfo)
throws Exception
{
return getIdAsVillageValue(connection, keyInfo).asString();
}
/**
* A flag to determine the timing of the id generation
*
* @return a <code>boolean</code> value
*/
public boolean isPriorToInsert()
{
return true;
}
/**
* A flag to determine the timing of the id generation
*
* @return a <code>boolean</code> value
*/
public boolean isPostInsert()
{
return false;
}
/**
* A flag to determine whether a Connection is required to
* generate an id.
*
* @return a <code>boolean</code> value
*/
public boolean isConnectionRequired()
{
return true;
}
/**
* Retrieves an id as a Village Value.
*
* @param connection A Connection.
* @param keyInfo an Object that contains additional info.
* @return A Village Value id.
* @exception Exception Database error.
*/
private Value getIdAsVillageValue(Connection connection, Object keyInfo)
throws Exception
{
String idSql = dbAdapter.getIDMethodSQL(keyInfo);
if (log.isDebugEnabled())
{
log.debug(idSql);
}
// Execute the query.
QueryDataSet qds = new QueryDataSet(connection, idSql);
Record rec;
try
{
qds.fetchRecords(1);
rec = qds.getRecord(0); // Records are 0 based.
}
finally
{
if (qds != null)
{
qds.close();
}
}
return rec.getValue(1); // Values are 1 based.
}
}