/*
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* JBoss, Home of Professional Open Source
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* Copyright 2005, JBoss Inc., and individual contributors as indicated
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* by the @authors tag. See the copyright.txt in the distribution for a
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* full listing of individual contributors.
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*
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* This is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This software is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this software; if not, write to the Free
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* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
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* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
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*/
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package org.jbpm.pvm.internal.query;
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import java.io.ObjectStreamException;
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import java.sql.SQLException;
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import java.util.List;
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import org.hibernate.HibernateException;
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import org.hibernate.Query;
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import org.hibernate.Session;
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import org.jbpm.api.JbpmException;
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import org.jbpm.api.cmd.Command;
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import org.jbpm.api.cmd.Environment;
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import org.jbpm.internal.log.Log;
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import org.jbpm.pvm.internal.cmd.CommandService;
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import org.jbpm.pvm.internal.env.EnvironmentImpl;
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/**
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* @author Tom Baeyens
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*/
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public abstract class AbstractQuery implements Command<Object> {
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private static Log log = Log.getLog(AbstractQuery.class.getName());
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private static final long serialVersionUID = 1L;
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protected CommandService commandService;
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protected String orderByClause = null;
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protected Page page = null;
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protected boolean isWhereAdded = false;
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protected boolean count = false;
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protected abstract void applyParameters(Query query);
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public abstract String hql();
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/* reuse by copy and paste:
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* (return type can't be changed)
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public ConcreteQuery page(int firstResult, int maxResults) {
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this.page = new Page(firstResult, maxResults);
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return this;
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}
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*/
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public List untypedList() {
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if (commandService!=null) {
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return (List) commandService.execute(this);
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}
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Session session = EnvironmentImpl.getFromCurrent(Session.class);
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return (List) execute(session);
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}
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protected Object untypedUniqueResult() {
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List list = untypedList();
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if (list.isEmpty()) {
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return null;
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}
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if (list.size()>1) {
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throw new JbpmException("result not unique: "+list.size());
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}
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return list.get(0);
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}
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public Object execute(Environment environment) throws Exception {
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Session session = environment.get(Session.class);
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return execute(session);
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}
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public Object execute(Session session) {
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String hql = hql();
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try {
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Query query = session.createQuery(hql);
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applyParameters(query);
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applyPage(query);
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return query.list();
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} catch (HibernateException e) {
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Throwable t = e;
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while (t!=null) {
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if (t instanceof SQLException) {
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SQLException sqlException = (SQLException) t;
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SQLException nextException = sqlException.getNextException();
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if (nextException!=null) {
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log.error("cause of "+nextException+": ", e);
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}
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}
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t = t.getCause();
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}
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throw e;
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} finally {
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resetQuery(); // reset the query member fields so the query can be reused.
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}
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}
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/**
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* Returns the count of the query.
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* Query types that want to use this count method should
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* - add the operation signature to their interface
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* - use the 'count' variable in their hql() method.
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*/
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public long count() {
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count = true;
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// Page and count cannot be used together, because paging is applied after the query is formed
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if (page != null) {
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throw new JbpmException("page(firstResult, maxResult) and count() cannot be used together");
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}
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return (Long) untypedUniqueResult();
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}
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/**
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* Resets the query so it can be reused after an invocation.
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*/
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private void resetQuery() {
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isWhereAdded = false;
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count = false;
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}
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protected void appendWhereClause(String whereClause, StringBuilder hql) {
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if (isWhereAdded) {
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hql.append(" and ");
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} else {
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isWhereAdded = true;
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hql.append("where ");
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}
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hql.append(whereClause);
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}
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protected void appendOrderByClause(StringBuilder hql) {
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if (orderByClause!=null) {
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hql.append("order by ");
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hql.append(orderByClause);
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}
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}
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protected void applyPage(Query query) {
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if (page!=null) {
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query.setFirstResult(page.firstResult);
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query.setMaxResults(page.maxResults);
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}
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}
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protected void addOrderByClause(String clause) {
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if (orderByClause==null) {
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orderByClause = clause;
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} else {
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orderByClause += ", " + clause;
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}
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}
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protected Object writeReplace() throws ObjectStreamException {
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this.commandService = null;
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return this;
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}
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public void setCommandService(CommandService commandService) {
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this.commandService = commandService;
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}
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}
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