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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
* 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
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package org.apache.cayenne.reflect;
import java.util.Collection;
import org.apache.cayenne.Fault;
import org.apache.cayenne.ValueHolder;
/**
* A generic superclass of CollectionProperty implementations.
*
* @since 1.2
*/
public abstract class BaseToManyProperty extends BaseArcProperty implements
ToManyProperty {
public BaseToManyProperty(ClassDescriptor owner, ClassDescriptor targetDescriptor,
Accessor accessor, String reverseName) {
super(owner, targetDescriptor, accessor, reverseName);
}
@Override
public Object readProperty(Object object) throws PropertyException {
return ensureCollectionValueHolderSet(object);
}
/**
* Wraps list in a value holder that performs lazy faulting.
*/
@Override
public void writePropertyDirectly(Object object, Object oldValue, Object newValue)
throws PropertyException {
if (newValue instanceof Fault) {
super.writePropertyDirectly(object, null, newValue);
}
else {
// must resolve value holder...
ValueHolder holder = (ValueHolder) readProperty(object);
holder.setValueDirectly(newValue);
}
}
public void addTarget(Object source, Object target, boolean setReverse) {
if (target == null) {
throw new NullPointerException("Attempt to add null object.");
}
// TODO, Andrus, 2/9/2006 - CayenneDataObject differences:
// * invokes "willConnect"
// * has a callback to ObjectStore to handle flattened
// * has a callback to ObjectStore to retain snapshot
// * changes object state to modified
// Now do the rest of the normal handling (regardless of whether it was
// flattened or not)
Collection<Object> collection = (Collection<Object>) readProperty(source);
collection.add(target);
if (setReverse) {
setReverse(source, null, target);
}
}
public void removeTarget(Object source, Object target, boolean setReverse) {
// TODO, Andrus, 2/9/2006 - CayenneDataObject differences:
// * has a callback to ObjectStore to handle flattened
// * changes object state to modified
// Now do the rest of the normal handling (regardless of whether it was
// flattened or not)
Collection<Object> collection = (Collection<Object>) readProperty(source);
collection.remove(target);
if (target != null && setReverse) {
setReverse(source, target, null);
}
}
@Override
public boolean visit(PropertyVisitor visitor) {
return visitor.visitToMany(this);
}
/**
* Injects a List in the object if it hasn't been done yet.
*/
@Override
public void injectValueHolder(Object object) throws PropertyException {
ensureCollectionValueHolderSet(object);
}
/**
* Checks that an object's List field described by this property is set, injecting a
* List if needed.
*/
protected ValueHolder ensureCollectionValueHolderSet(Object object)
throws PropertyException {
Object value = accessor.getValue(object);
if (value == null || value instanceof Fault) {
value = createCollectionValueHolder(object);
accessor.setValue(object, value);
}
return (ValueHolder) value;
}
/**
* Creates a Collection for an object.
*/
protected abstract ValueHolder createCollectionValueHolder(Object object)
throws PropertyException;
}