/*
* 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 java.sql.SQLException;
import org.apache.openjpa.jdbc.identifier.DBIdentifier;
import org.apache.openjpa.jdbc.kernel.JDBCStore;
import org.apache.openjpa.jdbc.meta.ClassMapping;
import org.apache.openjpa.jdbc.meta.DiscriminatorMappingInfo;
import org.apache.openjpa.jdbc.schema.Column;
import org.apache.openjpa.jdbc.schema.Index;
import org.apache.openjpa.jdbc.sql.DBDictionary;
import org.apache.openjpa.jdbc.sql.Joins;
import org.apache.openjpa.jdbc.sql.Result;
import org.apache.openjpa.jdbc.sql.Row;
import org.apache.openjpa.jdbc.sql.RowManager;
import org.apache.openjpa.jdbc.sql.SQLBuffer;
import org.apache.openjpa.jdbc.sql.Select;
import org.apache.openjpa.kernel.OpenJPAStateManager;
import org.apache.openjpa.lib.util.Localizer;
import org.apache.openjpa.meta.JavaTypes;
import org.apache.openjpa.util.MetaDataException;
/**
* Base discriminator strategy that determines the class of database
* records using a column holding a value mapped to a class, and limits
* SELECTs using an IN (...) statement.
*
* @author Abe White
*/
public abstract class InValueDiscriminatorStrategy
extends AbstractDiscriminatorStrategy {
private static final Localizer _loc = Localizer.forPackage
(InValueDiscriminatorStrategy.class);
/**
* Return the Java type code from {@link JavaTypes} for the discriminator
* values. This method is only used during mapping installation.
*/
protected abstract int getJavaType();
/**
* Return the discriminator value for the given type.
*/
protected abstract Object getDiscriminatorValue(ClassMapping cls);
/**
* Convert the given discriminator value to the corresponding class.
*/
protected abstract Class getClass(Object val, JDBCStore store)
throws ClassNotFoundException;
public void map(boolean adapt) {
ClassMapping cls = disc.getClassMapping();
if (cls.getJoinablePCSuperclassMapping() != null
|| cls.getEmbeddingMetaData() != null)
throw new MetaDataException(_loc.get("not-base-disc", cls));
DiscriminatorMappingInfo info = disc.getMappingInfo();
info.assertNoJoin(disc, true);
info.assertNoForeignKey(disc, !adapt);
info.assertNoUnique(disc, false);
Column tmplate = new Column();
tmplate.setJavaType(getJavaType());
DBDictionary dict = cls.getMappingRepository().getDBDictionary();
DBIdentifier typName = DBIdentifier.newColumn("typ", dict != null ? dict.delimitAll() : false);
tmplate.setIdentifier(typName);
Column[] cols = info.getColumns(disc, new Column[]{ tmplate }, adapt);
disc.setColumns(cols);
disc.setColumnIO(info.getColumnIO());
Index idx = info.getIndex(disc, cols, adapt);
disc.setIndex(idx);
}
public void insert(OpenJPAStateManager sm, JDBCStore store, RowManager rm)
throws SQLException {
Row row = rm.getRow(disc.getClassMapping().getTable(),
Row.ACTION_INSERT, sm, true);
Object cls = getDiscriminatorValue((ClassMapping) sm.getMetaData());
if (disc.getColumnIO().isInsertable(0, cls == null))
row.setObject(disc.getColumns()[0], cls);
}
public boolean select(Select sel, ClassMapping mapping) {
if (isFinal)
return false;
sel.select(disc.getColumns());
return true;
}
public Class getClass(JDBCStore store, ClassMapping base, Result res)
throws SQLException, ClassNotFoundException {
if (isFinal
|| !useDiscrimColumn(base, res)
|| (base.getPCSuperclass() == null && base.getJoinablePCSubclassMappings().length == 0)) {
return base.getDescribedType();
}
Object cls = res.getObject(disc.getColumns()[0], disc.getJavaType(), null);
return getClass(cls, store);
}
private final boolean useDiscrimColumn(ClassMapping base, Result res) throws SQLException {
if (res.getBaseMapping() != null && base != null) {
// check whether the result type is assignable to the base mapping.
// if not assignable the discriminator value will not be correct.
if (!base.getDescribedType().isAssignableFrom(res.getBaseMapping().getDescribedType())) {
return false;
}
}
return res.contains(disc.getColumns()[0]);
}
public boolean hasClassConditions(ClassMapping base, boolean subclasses) {
// if selecting the first mapped class and all subclasses, no need
// to limit the query
if (isFinal || (base.getJoinablePCSuperclassMapping() == null
&& subclasses))
return false;
// if no subclasses or superclass, no need for conditions
ClassMapping[] subs = base.getJoinablePCSubclassMappings();
if (subs.length == 0 && base.getJoinablePCSuperclassMapping() == null)
return false;
return true;
}
public SQLBuffer getClassConditions(Select sel, Joins joins,
ClassMapping base, boolean subclasses) {
Column col = disc.getColumns()[0];
SQLBuffer sql = new SQLBuffer(sel.getConfiguration().
getDBDictionaryInstance());
String alias = sel.getColumnAlias(col, joins);
boolean outer = joins != null && joins.isOuter();
if (outer)
sql.append("(");
sql.append(alias);
// if not selecting subclasses, limit to just the given class
ClassMapping[] subs = base.getJoinablePCSubclassMappings();
if (!outer && (!subclasses || subs.length == 0))
return sql.append(" = ").appendValue(getDiscriminatorValue(base),
col);
if (outer)
sql.append(" IS ").appendValue(null).append(" OR ").append(alias);
sql.append(" IN (");
sql.appendValue(getDiscriminatorValue(base), col);
for (int i = 0; i < subs.length; i++)
sql.append(", ").appendValue(getDiscriminatorValue(subs[i]), col);
sql.append(")");
if (outer)
sql.append(")");
return sql;
}
}