org.tentackle.dbms.IgnoreDuplicatesPersistenceVisitor Maven / Gradle / Ivy
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/**
* Tentackle - http://www.tentackle.org
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package org.tentackle.dbms;
import java.util.HashSet;
import java.util.Set;
import org.tentackle.log.Logger;
import org.tentackle.log.LoggerFactory;
/**
* A visitor to ignore duplicates within a persistence operation.
* Used to avoid duplicate key errors, for example, if components are referenced more than once
* within the same root entity.
*
* @author harald
*/
public class IgnoreDuplicatesPersistenceVisitor extends PersistenceVisitor {
/**
* logger for this class.
*/
private static final Logger LOGGER = LoggerFactory.getLogger(IgnoreDuplicatesPersistenceVisitor.class);
/** seriialUID. */
private static final long serialVersionUID = 8166893128074169609L;
private final Set> objectSet; // all persisted objects so far
private boolean persistenceOperationAllowed; // true if allowed
/**
* Creates the visitor.
*/
public IgnoreDuplicatesPersistenceVisitor() {
objectSet = new HashSet<>();
}
/**
* Visits all objects.
*
* This is the dispatched method!
*
* @param object the object
* @param modType the modification type (ignored)
*/
public void visit(AbstractDbObject object, Character modType) {
persistenceOperationAllowed = objectSet.add(object);
}
/**
* Checks whether object has already been persisted.
*
* @param object the persistable object
* @param modType the modification type (ignored)
* @return true if object has not been persisted already
*/
@Override
public boolean isPersistenceOperationAllowed(AbstractDbObject object, char modType) {
if (!persistenceOperationAllowed && LOGGER.isInfoLoggable()) {
LOGGER.info(object.toGenericString() + " already persisted -> '" + modType + "' ignored");
}
return persistenceOperationAllowed;
}
}