Re: [NEWBIE] your advice pleeeeeeease

Thomas Mahler Mon, 30 Jun 2003 11:53:29 -0700

Hi!

from an OJB standpoint it looks OK.

If you want to use the interface IPersistenceService as an abstraction of the concrete persistence layer I have some doubts.

The Methods public Object getObjectByCriteria(Class clazz, Criteria criteria) and public Collection getCollectionByCriteria(Class clazz, Criteria criteria) both have a Criteria parameter. Criteria is part of the OJB query package and so your interface contains a dependency on OJB. If you choose to work exclusively with OJB this is OK, but if you want to plugin different O/R layers you'll have to translate OJB Criteria to the query API of the other tool!

The method public Object getObjectById(Class clazz, int id) does only accept a single int column and you statically refer to the "id" field as PK field. This is a hard restriction on both object model and relational schema. Maybe it's OK for your current project, but what will you do if the next project has to use a legacy database with compound primary keys.

just my 2 cent,

cheers,
Thomas

Youness Afid wrote:

hi,
sorry for this noisy mail, but can any guru here tell me if my persistence
service is well done ??
thanks a lot in advance

----------------------------------------------------------------------------
----------------------------
package services.persistence;

import java.util.Collection;

import org.apache.ojb.broker.PersistenceBroker;
import org.apache.ojb.broker.PersistenceBrokerFactory;
import org.apache.ojb.broker.query.Criteria;
import org.apache.ojb.broker.query.Query;
import org.apache.ojb.broker.query.QueryByCriteria;

import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.Log;

import services.exception.ExceptionService;

public class PersistenceService implements IPersistenceService {

private Log log = LogFactory.getLog(PersistenceService.class);

        private PersistenceBroker getBroker() throws Exception {
                PersistenceBroker broker = null;
                try {
                        broker =
PersistenceBrokerFactory.defaultPersistenceBroker();
                } catch (Throwable t) {
                        log.error(t);
        
ExceptionService.getInstance().throwException(ExceptionService.FATAL,
ExceptionService.OJB_BROKERINSTANCIATION);
                }
                return broker;
        }

        public void storeObject(Object object) throws Exception {
                PersistenceBroker broker = getBroker();
                try {
                        broker.beginTransaction();
                        broker.store(object);
                        broker.commitTransaction();
                } catch (Exception e1) {
                        try {
                                broker.abortTransaction();
                        } catch (Exception e2) {
                                log.error(e2);
        
ExceptionService.getInstance().throwException(ExceptionService.MESSAGENAME,
ExceptionService.OJB_TRANSACTION);
                        }
                        log.error(e1);
        
ExceptionService.getInstance().throwException(ExceptionService.MESSAGENAME,
ExceptionService.OJB_STORE);
                }
        }

        public void deleteObject(Object object) throws Exception {
                PersistenceBroker broker = getBroker();
                try {
                        broker.beginTransaction();
                        broker.delete(object);
                        broker.commitTransaction();
                } catch (Exception e1) {
                        try {
                                broker.abortTransaction();
                        } catch (Exception e2) {
                                log.error(e2);
        
ExceptionService.getInstance().throwException(ExceptionService.MESSAGENAME,
ExceptionService.OJB_TRANSACTION);
                        }
                        log.error(e1);
        
ExceptionService.getInstance().throwException(ExceptionService.MESSAGENAME,
ExceptionService.OJB_STORE);
                }
        }

        public Object getObjectByCriteria(Class clazz, Criteria criteria) {
                Object object = null;
                Query query = new QueryByCriteria(clazz, criteria);
                try {
                        object = getBroker().getObjectByQuery(query);
                } catch (Throwable t) {
                        log.error(t);
        
ExceptionService.getInstance().addError(ExceptionService.MESSAGENAME,
ExceptionService.OJB_GETCOLLECTION);
                }
                return object;
        }

        public Object getObjectById(Class clazz, int id) {
                Criteria criteria = new Criteria();
                criteria.addEqualTo("id", String.valueOf(id));
                return getObjectByCriteria(clazz, criteria);
        }

        public Collection getCollectionByCriteria(Class clazz, Criteria
criteria) {
                Collection collection = null;
                Query query = new QueryByCriteria(clazz, criteria);
                try {
                        collection =
getBroker().getCollectionByQuery(query);
                } catch (Throwable t) {
                        log.error(t);
        
ExceptionService.getInstance().addError(ExceptionService.MESSAGENAME,
ExceptionService.OJB_GETCOLLECTION);
                }
                return collection;

}

}

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