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* 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
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*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
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* KIND, either express or implied. See the License for the
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package org.apache.cayenne.reflect.valueholder;
import org.apache.cayenne.Persistent;
import org.apache.cayenne.ValueHolder;
import org.apache.cayenne.reflect.Accessor;
import org.apache.cayenne.reflect.BaseToOneProperty;
import org.apache.cayenne.reflect.ClassDescriptor;
import org.apache.cayenne.reflect.PropertyException;
import org.apache.cayenne.util.PersistentObjectHolder;
/**
* Provides access to a property implemented as a {@link ValueHolder} Field. This
* implementation hides the fact of the ValueHolder existence. I.e. it never returns it
* from 'readPropertyDirectly', returning held value instead.
*
* @since 3.0
* @author Andrus Adamchik
*/
class ValueHolderProperty extends BaseToOneProperty {
ValueHolderProperty(ClassDescriptor owner, ClassDescriptor targetDescriptor,
Accessor accessor, String reverseName) {
super(owner, targetDescriptor, accessor, reverseName);
}
/**
* Returns true if a property ValueHolder is not initialized or is itself a fault.
*/
@Override
public boolean isFault(Object object) {
ValueHolder holder = (ValueHolder) accessor.getValue(object);
return holder == null || holder.isFault();
}
public void invalidate(Object object) {
ValueHolder holder = (ValueHolder) accessor.getValue(object);
if (holder != null && !holder.isFault()) {
holder.invalidate();
}
}
@Override
public Object readPropertyDirectly(Object object) throws PropertyException {
ValueHolder holder = (ValueHolder) accessor.getValue(object);
// TODO: Andrus, 2/9/2006 ValueHolder will resolve an object in a call to
// 'getValue'; this is inconsistent with 'readPropertyDirectly' contract
return (holder != null) ? holder.getValueDirectly() : null;
}
@Override
public Object readProperty(Object object) throws PropertyException {
return ensureValueHolderSet(object).getValue();
}
@Override
public void writePropertyDirectly(Object object, Object oldValue, Object newValue)
throws PropertyException {
ValueHolder holder = (ValueHolder) accessor.getValue(object);
if (holder == null) {
holder = createValueHolder(object);
accessor.setValue(object, holder);
}
holder.setValueDirectly(newValue);
}
@Override
public void writeProperty(Object object, Object oldValue, Object newValue)
throws PropertyException {
ensureValueHolderSet(object).setValueDirectly(newValue);
}
/**
* Injects a ValueHolder in the object if it hasn't been done yet.
*/
@Override
public void injectValueHolder(Object object) throws PropertyException {
ensureValueHolderSet(object);
}
/**
* Checks that an object's ValueHolder field described by this property is set,
* injecting a ValueHolder if needed.
*/
protected ValueHolder ensureValueHolderSet(Object object) throws PropertyException {
ValueHolder holder = (ValueHolder) accessor.getValue(object);
if (holder == null) {
holder = createValueHolder(object);
accessor.setValue(object, holder);
}
return holder;
}
/**
* Creates a ValueHolder for an object. Default implementation requires that an object
* implements Persistent interface.
*/
protected ValueHolder createValueHolder(Object object) throws PropertyException {
if (!(object instanceof Persistent)) {
throw new PropertyException(
"ValueHolders for non-persistent objects are not supported.",
this,
object);
}
return new PersistentObjectHolder((Persistent) object, getName());
}
}