| /* |
| * 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 { |
| |
| |
| private static final long serialVersionUID = 1L; |
| |
| /** |
| * 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); |
| |
| @Override |
| public void appendIsEmpty(SQLBuffer sql, Select sel, Joins joins) { |
| testEmpty(sql, sel, joins, true); |
| } |
| |
| @Override |
| public void appendIsNotEmpty(SQLBuffer sql, Select sel, Joins joins) { |
| testEmpty(sql, sel, joins, false); |
| } |
| |
| @Override |
| public void appendIsNull(SQLBuffer sql, Select sel, Joins joins) { |
| testEmpty(sql, sel, joins, true); |
| } |
| |
| @Override |
| 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(); |
| |
| @Override |
| 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); |
| } |
| |
| @Override |
| 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]); |
| } |
| } |
| } |