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/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2013, Red Hat Inc. 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 Inc.
*
* 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.internal.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.internal.tools.MutableInteger;
import org.hibernate.envers.internal.tools.StringTools;
import org.hibernate.envers.tools.Pair;
/**
* A class for incrementally 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> froms;
/**
* A list of pairs (property name, order ascending?).
*/
private final List> orders;
/**
* A list of complete projection definitions: either a sole property name, or a function(property name).
*/
private final List 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>();
orders = new ArrayList>();
projections = new ArrayList();
addFrom( entityName, alias );
}
// Only for deep copy purpose.
private QueryBuilder(QueryBuilder other) {
this.entityName = other.entityName;
this.alias = other.alias;
this.aliasCounter = other.aliasCounter.deepCopy();
this.paramCounter = other.paramCounter.deepCopy();
this.rootParameters = other.rootParameters.deepCopy();
froms = new ArrayList>( other.froms );
orders = new ArrayList>( other.orders );
projections = new ArrayList( other.projections );
}
public QueryBuilder deepCopy() {
return new QueryBuilder( this );
}
/**
* 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 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 getAliasList() {
final List aliasList = new ArrayList();
for ( Pair from : froms ) {
aliasList.add( from.getSecond() );
}
return aliasList;
}
public String getRootAlias() {
return alias;
}
private List getFromList() {
final List fromList = new ArrayList();
for ( Pair from : froms ) {
fromList.add( from.getFirst() + " " + from.getSecond() );
}
return fromList;
}
private List getOrderList() {
final List orderList = new ArrayList();
for ( Pair order : orders ) {
orderList.add( alias + "." + order.getFirst() + " " + (order.getSecond() ? "asc" : "desc") );
}
return orderList;
}
public Query toQuery(Session session) {
final StringBuilder querySb = new StringBuilder();
final Map queryParamValues = new HashMap();
build( querySb, queryParamValues );
final Query query = session.createQuery( querySb.toString() );
for ( Map.Entry paramValue : queryParamValues.entrySet() ) {
query.setParameter( paramValue.getKey(), paramValue.getValue() );
}
return query;
}
}