/*****************************************************************
* 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.cayenne.util;
import java.util.ArrayList;
import java.util.List;
import org.apache.cayenne.PersistenceState;
import org.apache.cayenne.Persistent;
import org.apache.cayenne.map.EntityResolver;
import org.apache.cayenne.map.ObjEntity;
import org.apache.cayenne.map.ObjRelationship;
import org.apache.cayenne.query.RelationshipQuery;
import org.apache.cayenne.reflect.PropertyDescriptor;
/**
* An abstract superclass of lazily faulted to-one and to-many relationships.
*
* @since 1.2
*/
public abstract class RelationshipFault {
protected Persistent relationshipOwner;
protected String relationshipName;
protected RelationshipFault() {
}
public RelationshipFault(Persistent relationshipOwner, String relationshipName) {
if (relationshipOwner == null) {
throw new NullPointerException("'relationshipOwner' can't be null.");
}
if (relationshipName == null) {
throw new NullPointerException("'relationshipName' can't be null.");
}
this.relationshipOwner = relationshipOwner;
this.relationshipName = relationshipName;
}
public String getRelationshipName() {
return relationshipName;
}
public Persistent getRelationshipOwner() {
return relationshipOwner;
}
protected boolean isTransientParent() {
int state = relationshipOwner.getPersistenceState();
return state == PersistenceState.NEW || state == PersistenceState.TRANSIENT;
}
protected boolean isUncommittedParent() {
int state = relationshipOwner.getPersistenceState();
return state == PersistenceState.MODIFIED || state == PersistenceState.DELETED;
}
protected abstract void mergeLocalChanges(List resolved);
/**
* Executes a query that returns related objects. Subclasses would invoke this method
* whenever they need to resolve a fault.
*/
protected List resolveFromDB() {
// non-persistent objects shouldn't trigger a fetch
if (isTransientParent()) {
return new ArrayList();
}
List resolved = relationshipOwner.getObjectContext().performQuery(
new RelationshipQuery(relationshipOwner.getObjectId(), relationshipName, false));
/**
* Duplicating the list (see CAY-1194). Doing that only for
* RelationshipFault query results, so only for nested DataContexts
*/
if (resolved instanceof RelationshipFault) {
resolved = new ArrayList(resolved);
}
// merge local before updating reverse to ensure we update reverse rels
// of the right objects (see CAY-1757)
mergeLocalChanges(resolved);
if (resolved.isEmpty()) {
return resolved;
}
updateReverse(resolved);
return resolved;
}
// see if reverse relationship is to-one and we can connect source to results....
protected void updateReverse(List resolved) {
EntityResolver resolver = relationshipOwner
.getObjectContext()
.getEntityResolver();
ObjEntity sourceEntity = resolver.getObjEntity(relationshipOwner
.getObjectId()
.getEntityName());
ObjRelationship relationship = (ObjRelationship) sourceEntity
.getRelationship(relationshipName);
ObjRelationship reverse = relationship.getReverseRelationship();
if (reverse != null && !reverse.isToMany()) {
PropertyDescriptor property = resolver.getClassDescriptor(
reverse.getSourceEntity().getName()).getProperty(reverse.getName());
for(Object o : resolved) {
property.writePropertyDirectly(o, null, relationshipOwner);
}
}
}
}