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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.openjpa.jdbc.meta.strats;
import org.apache.openjpa.jdbc.meta.ClassMapping;
import org.apache.openjpa.jdbc.meta.FieldMapping;
import org.apache.openjpa.jdbc.meta.ValueMapping;
import org.apache.openjpa.jdbc.schema.Column;
import org.apache.openjpa.jdbc.schema.ForeignKey;
import org.apache.openjpa.jdbc.sql.DBDictionary;
import org.apache.openjpa.jdbc.sql.Joins;
import org.apache.openjpa.jdbc.sql.SQLBuffer;
import org.apache.openjpa.jdbc.sql.Select;
/**
* An abstract container mapping that handles traversing the
* join to examine the size of the relation.
*
* @author Marc Prud'hommeaux
*/
public abstract class ContainerFieldStrategy
extends AbstractFieldStrategy {
/**
* Return all independent mappings to which this strategy must join in
* order to access collection elements, or empty array if none.
*
* @param traverse whether we're traversing through to the related type
* @see ValueMapping#getIndependentTypeMappings
* @see ClassMapping#EMPTY_MAPPINGS
*/
protected abstract ClassMapping[] getIndependentElementMappings
(boolean traverse);
public void appendIsEmpty(SQLBuffer sql, Select sel, Joins joins) {
testEmpty(sql, sel, joins, true);
}
public void appendIsNotEmpty(SQLBuffer sql, Select sel, Joins joins) {
testEmpty(sql, sel, joins, false);
}
public void appendIsNull(SQLBuffer sql, Select sel, Joins joins) {
testEmpty(sql, sel, joins, true);
}
public void appendIsNotNull(SQLBuffer sql, Select sel, Joins joins) {
testEmpty(sql, sel, joins, false);
}
/**
* Appends SQL for a sub-select testing whether the container is empty.
*/
private void testEmpty(SQLBuffer sql, Select sel, Joins joins,
boolean empty) {
if (empty)
sql.append("0 = ");
else
sql.append("0 < ");
appendSize(sql, sel, joins);
}
public abstract ForeignKey getJoinForeignKey();
public void appendSize(SQLBuffer sql, Select sel, Joins joins) {
DBDictionary dict = field.getMappingRepository().getDBDictionary();
dict.assertSupport(dict.supportsSubselect, "SupportsSubselect");
ClassMapping[] ind = getIndependentElementMappings(false);
if (ind != null && ind.length > 1)
throw RelationStrategies.unjoinable(field);
ForeignKey fk = getJoinForeignKey();
appendJoinCount(sql, sel, joins, dict, field, fk);
}
public void appendIndex(SQLBuffer sql, Select sel, Joins joins) {
sql.append(sel.getColumnAlias(field.getOrderColumn(),
field.getName()));
}
protected static void appendJoinCount(SQLBuffer sql, Select sel,
Joins joins, DBDictionary dict, FieldMapping field, ForeignKey fk) {
String fullTable = dict.getFullName(fk.getTable(), false);
sql.append("(SELECT COUNT(*) FROM ").append(fullTable).
append(" WHERE ");
appendUnaliasedJoin(sql, sel, joins, dict, field, fk);
sql.append(")");
}
public static void appendUnaliasedJoin(SQLBuffer sql, Select sel,
Joins joins, DBDictionary dict, FieldMapping field, ForeignKey fk) {
String fullTable = dict.getFullName(fk.getTable(), false);
Column[] cols = fk.getColumns();
Column[] pks = fk.getPrimaryKeyColumns();
int count = 0;
for (int i = 0; i < cols.length; i++, count++) {
if (count > 0)
sql.append(" AND ");
sql.append(fullTable).append(".").append(cols[i]).append(" = ").
append(sel.getColumnAlias(pks[i], joins));
}
cols = fk.getConstantColumns();
for (int i = 0; i < cols.length; i++, count++) {
if (count > 0)
sql.append(" AND ");
sql.append(fullTable).append(".").append(cols[i]).append(" = ").
appendValue(fk.getConstant(cols[i]), cols[i]);
}
pks = fk.getConstantPrimaryKeyColumns();
for (int i = 0; i < pks.length; i++, count++) {
if (count > 0)
sql.append(" AND ");
sql.append(sel.getColumnAlias(pks[i], joins)).append(" = ").
appendValue(fk.getPrimaryKeyConstant(pks[i]), pks[i]);
}
}
}