/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Middleware LLC.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program 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 distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.envers.tools.query;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.envers.tools.MutableInteger;
import org.hibernate.envers.tools.Pair;
import org.hibernate.envers.tools.StringTools;
/**
* A class for incrementaly building a HQL query.
* @author Adam Warski (adam at warski dot org)
*/
public class QueryBuilder {
private final String entityName;
private final String alias;
/**
* For use by alias generator (in case an alias is not provided by the user).
*/
private final MutableInteger aliasCounter;
/**
* For use by parameter generator, in {@link Parameters}. This counter must be
* the same in all parameters and sub-queries of this query.
*/
private final MutableInteger paramCounter;
/**
* Main "where" parameters for this query.
*/
private final Parameters rootParameters;
/**
* A list of pairs (from entity name, alias name).
*/
private final List<Pair<String, String>> froms;
/**
* A list of pairs (property name, order ascending?).
*/
private final List<Pair<String, Boolean>> orders;
/**
* A list of complete projection definitions: either a sole property name, or a function(property name).
*/
private final List<String> projections;
/**
*
* @param entityName Main entity which should be selected.
* @param alias Alias of the entity
*/
public QueryBuilder(String entityName, String alias) {
this(entityName, alias, new MutableInteger(), new MutableInteger());
}
private QueryBuilder(String entityName, String alias, MutableInteger aliasCounter, MutableInteger paramCounter) {
this.entityName = entityName;
this.alias = alias;
this.aliasCounter = aliasCounter;
this.paramCounter = paramCounter;
rootParameters = new Parameters(alias, "and", paramCounter);
froms = new ArrayList<Pair<String, String>>();
orders = new ArrayList<Pair<String, Boolean>>();
projections = new ArrayList<String>();
addFrom(entityName, alias);
}
/**
* Add an entity from which to select.
* @param entityName Name of the entity from which to select.
* @param alias Alias of the entity. Should be different than all other aliases.
*/
public void addFrom(String entityName, String alias) {
froms.add(Pair.make(entityName, alias));
}
private String generateAlias() {
return "_e" + aliasCounter.getAndIncrease();
}
/**
* @return A sub-query builder for the same entity (with an auto-generated alias). The sub-query can
* be later used as a value of a parameter.
*/
public QueryBuilder newSubQueryBuilder() {
return newSubQueryBuilder(entityName, generateAlias());
}
/**
* @param entityName Entity name, which will be the main entity for the sub-query.
* @param alias Alias of the entity, which can later be used in parameters.
* @return A sub-query builder for the given entity, with the given alias. The sub-query can
* be later used as a value of a parameter.
*/
public QueryBuilder newSubQueryBuilder(String entityName, String alias) {
return new QueryBuilder(entityName, alias, aliasCounter, paramCounter);
}
public Parameters getRootParameters() {
return rootParameters;
}
public void addOrder(String propertyName, boolean ascending) {
orders.add(Pair.make(propertyName, ascending));
}
public void addProjection(String function, String propertyName, boolean distinct) {
addProjection(function, propertyName, distinct, true);
}
public void addProjection(String function, String propertyName, boolean distinct, boolean addAlias) {
if (function == null) {
projections.add((distinct ? "distinct " : "") + (addAlias ? alias+ "." : "") + propertyName);
} else {
projections.add(function + "(" + (distinct ? "distinct " : "") + (addAlias ? alias + "." : "") + propertyName + ")");
}
}
/**
* Builds the given query, appending results to the given string buffer, and adding all query parameter values
* that are used to the map provided.
* @param sb String builder to which the query will be appended.
* @param queryParamValues Map to which name and values of parameters used in the query should be added.
*/
public void build(StringBuilder sb, Map<String, Object> queryParamValues) {
sb.append("select ");
if (projections.size() > 0) {
// all projections separated with commas
StringTools.append(sb, projections.iterator(), ", ");
} else {
// all aliases separated with commas
StringTools.append(sb, getAliasList().iterator(), ", ");
}
sb.append(" from ");
// all from entities with aliases, separated with commas
StringTools.append(sb, getFromList().iterator(), ", ");
// where part - rootParameters
if (!rootParameters.isEmpty()) {
sb.append(" where ");
rootParameters.build(sb, queryParamValues);
}
// orders
if (orders.size() > 0) {
sb.append(" order by ");
StringTools.append(sb, getOrderList().iterator(), ", ");
}
}
private List<String> getAliasList() {
List<String> aliasList = new ArrayList<String>();
for (Pair<String, String> from : froms) {
aliasList.add(from.getSecond());
}
return aliasList;
}
private List<String> getFromList() {
List<String> fromList = new ArrayList<String>();
for (Pair<String, String> from : froms) {
fromList.add(from.getFirst() + " " + from.getSecond());
}
return fromList;
}
private List<String> getOrderList() {
List<String> orderList = new ArrayList<String>();
for (Pair<String, Boolean> order : orders) {
orderList.add(alias + "." + order.getFirst() + " " + (order.getSecond() ? "asc" : "desc"));
}
return orderList;
}
public Query toQuery(Session session) {
StringBuilder querySb = new StringBuilder();
Map<String, Object> queryParamValues = new HashMap<String, Object>();
build(querySb, queryParamValues);
Query query = session.createQuery(querySb.toString());
for (Map.Entry<String, Object> paramValue : queryParamValues.entrySet()) {
query.setParameter(paramValue.getKey(), paramValue.getValue());
}
return query;
}
}