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* distributed with this work for additional information
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* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
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*
* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.cayenne.access;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.Map;
import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.DeleteDenyException;
import org.apache.cayenne.PersistenceState;
import org.apache.cayenne.Persistent;
import org.apache.cayenne.map.DeleteRule;
import org.apache.cayenne.map.LifecycleEvent;
import org.apache.cayenne.map.ObjRelationship;
import org.apache.cayenne.reflect.ArcProperty;
import org.apache.cayenne.reflect.AttributeProperty;
import org.apache.cayenne.reflect.ClassDescriptor;
import org.apache.cayenne.reflect.PropertyVisitor;
import org.apache.cayenne.reflect.ToManyProperty;
import org.apache.cayenne.reflect.ToOneProperty;
/**
* Helper class that implements DataObject deletion strategy.
*
* @since 1.2
*/
class DataContextDeleteAction {
DataContext dataContext;
DataContextDeleteAction(DataContext context) {
this.dataContext = context;
}
/**
* Deletes internal DataObject from its DataContext, processing delete rules.
*/
boolean performDelete(Persistent object) throws DeleteDenyException {
int oldState = object.getPersistenceState();
if (oldState == PersistenceState.DELETED
|| oldState == PersistenceState.TRANSIENT) {
// Drop out... especially in case of DELETED we might be about to get
// into a horrible recursive loop due to CASCADE delete rules.
// Assume that everything must have been done correctly already
// and *don't* do it again
return false;
}
if (object.getObjectContext() == null) {
throw new CayenneRuntimeException(
"Attempt to delete unregistered non-TRANSIENT object: " + object);
}
if (object.getObjectContext() != dataContext) {
throw new CayenneRuntimeException(
"Attempt to delete object registered in a different DataContext. Object: "
+ object
+ ", data context: "
+ dataContext);
}
// must resolve HOLLOW objects before delete... needed
// to process relationships and optimistic locking...
dataContext.prepareForAccess(object, null, false);
if (oldState == PersistenceState.NEW) {
deleteNew(object, oldState);
}
else {
deletePersistent(object, oldState);
}
return true;
}
private void deletePersistent(Persistent object, int oldState)
throws DeleteDenyException {
dataContext.getEntityResolver().getCallbackRegistry().performCallbacks(
LifecycleEvent.PRE_REMOVE,
object);
object.setPersistenceState(PersistenceState.DELETED);
dataContext.getObjectStore().nodeRemoved(object.getObjectId());
processDeleteRules(object, oldState);
}
private void deleteNew(Persistent object, int oldState) throws DeleteDenyException {
object.setPersistenceState(PersistenceState.TRANSIENT);
processDeleteRules(object, oldState);
// if an object was NEW, we must throw it out of the ObjectStore
dataContext.getObjectStore().objectsUnregistered(
Collections.singletonList(object));
object.setObjectContext(null);
}
private Collection toCollection(Object object) {
if (object == null) {
return Collections.EMPTY_LIST;
}
// create copies of collections to avoid iterator exceptions
if (object instanceof Collection) {
return new ArrayList((Collection) object);
}
else if (object instanceof Map) {
return new ArrayList(((Map) object).values());
}
else {
return Collections.singleton(object);
}
}
private void processDeleteRules(final Persistent object, int oldState)
throws DeleteDenyException {
ClassDescriptor descriptor = dataContext.getEntityResolver().getClassDescriptor(
object.getObjectId().getEntityName());
for (final ObjRelationship relationship : descriptor.getEntity().getRelationships()) {
boolean processFlattened = relationship.isFlattened()
&& relationship.isToDependentEntity()
&& !relationship.isReadOnly();
// first check for no action... bail out if no flattened processing is needed
if (relationship.getDeleteRule() == DeleteRule.NO_ACTION && !processFlattened) {
continue;
}
ArcProperty property = (ArcProperty) descriptor.getProperty(relationship
.getName());
Collection relatedObjects = toCollection(property.readProperty(object));
// no related object, bail out
if (relatedObjects.size() == 0) {
continue;
}
// process DENY rule first...
if (relationship.getDeleteRule() == DeleteRule.DENY) {
object.setPersistenceState(oldState);
String message = relatedObjects.size() == 1
? "1 related object"
: relatedObjects.size() + " related objects";
throw new DeleteDenyException(object, relationship.getName(), message);
}
// process flattened with dependent join tables...
// joins must be removed even if they are non-existent or ignored in the
// object graph
if (processFlattened) {
ObjectStore objectStore = dataContext.getObjectStore();
Iterator iterator = relatedObjects.iterator();
while (iterator.hasNext()) {
Persistent relatedObject = (Persistent) iterator.next();
objectStore.arcDeleted(object.getObjectId(), relatedObject
.getObjectId(), relationship.getName());
}
}
// process remaining rules
switch (relationship.getDeleteRule()) {
case DeleteRule.NO_ACTION:
break;
case DeleteRule.NULLIFY:
ArcProperty reverseArc = property.getComplimentaryReverseArc();
if (reverseArc == null) {
// nothing we can do here
break;
}
final Collection finalRelatedObjects = relatedObjects;
reverseArc.visit(new PropertyVisitor() {
public boolean visitAttribute(AttributeProperty property) {
return false;
}
public boolean visitToMany(ToManyProperty property) {
Iterator iterator = finalRelatedObjects.iterator();
while (iterator.hasNext()) {
Object relatedObject = iterator.next();
property.removeTarget(relatedObject, object, true);
}
return false;
}
public boolean visitToOne(ToOneProperty property) {
// Inverse is to-one - find all related objects and
// nullify the reverse relationship
Iterator iterator = finalRelatedObjects.iterator();
while (iterator.hasNext()) {
Object relatedObject = iterator.next();
property.setTarget(relatedObject, null, true);
}
return false;
}
});
break;
case DeleteRule.CASCADE:
// Delete all related objects
Iterator iterator = relatedObjects.iterator();
while (iterator.hasNext()) {
Persistent relatedObject = (Persistent) iterator.next();
new DataContextDeleteAction(this.dataContext)
.performDelete(relatedObject);
}
break;
default:
object.setPersistenceState(oldState);
throw new CayenneRuntimeException("Invalid delete rule "
+ relationship.getDeleteRule());
}
}
}
}