org.eclipse.persistence.descriptors.TablePerClassPolicy Maven / Gradle / Ivy
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/*
* Copyright (c) 1998, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0,
* or the Eclipse Distribution License v. 1.0 which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
*/
// Contributors:
// 12/12/2008-1.1 Guy Pelletier
// - 249860: Implement table per class inheritance support.
package org.eclipse.persistence.descriptors;
import org.eclipse.persistence.exceptions.DescriptorException;
import org.eclipse.persistence.queries.ReadAllQuery;
import org.eclipse.persistence.queries.ReadObjectQuery;
/**
* Purpose: Provides the functionality to support a TABLE_PER_CLASS
* inheritance strategy. Resolves relational mappings and querying.
*/
public class TablePerClassPolicy extends InterfacePolicy {
/**
* INTERNAL:
* Create a new policy.
* Only descriptors involved in inheritance should have a policy.
*/
public TablePerClassPolicy(ClassDescriptor descriptor) {
setDescriptor(descriptor);
}
/**
* INTERNAL:
*/
public boolean isTablePerClassPolicy() {
return true;
}
/**
* INTERNAL:
* Select all objects for a concrete descriptor.
*/
@Override
protected Object selectAllObjects(ReadAllQuery query) {
if (this.descriptor.isAbstract()) {
return query.getContainerPolicy().containerInstance();
}
return super.selectAllObjects(query);
}
/**
* INTERNAL:
* Select one object of any concrete subclass.
*/
@Override
protected Object selectOneObject(ReadObjectQuery query) throws DescriptorException {
if (this.descriptor.isAbstract()) {
return null;
}
return super.selectOneObject(query);
}
}