de.alpharogroup.model

Class LoadableDetachableModel<T>

java.lang.Object

de.alpharogroup.model.LoadableDetachableModel<T>

Type Parameters:

T - The Model Object type

All Implemented Interfaces:

IDetachable, IModel<T>, Serializable

public abstract class LoadableDetachableModel<T>
extends Object
implements IModel<T>

Model that makes working with detachable models a breeze. LoadableDetachableModel holds a temporary, transient model object, that is set when getObject() is called by calling abstract method 'load', and that will be reset/ set to null on detach(). A usage example:

 LoadableDetachableModel venueListModel = new LoadableDetachableModel()
 {
        protected Object load()
        {
                return getVenueDao().findVenues();
        }
 };
 

Though you can override methods onAttach() and onDetach() for additional attach/ detach behavior, the point of this class is to hide as much of the attaching/ detaching as possible. So you should rarely need to override those methods, if ever.

Author:

Eelco Hillenius, Igor Vaynberg

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
LoadableDetachableModel() Construct.
LoadableDetachableModel(T object) This constructor is used if you already have the object retrieved and want to wrap it with a detachable model.

Method Summary

Modifier and Type	Method and Description
void	detach() Detaches model after use.
T	getObject() Note: If load() fails with an exception then null is kept as the attached value.
boolean	isAttached() Gets the attached status of this model instance
protected abstract T	load() Loads and returns the (temporary) model object.
protected void	onAttach() Attaches to the current request.
protected void	onDetach() Detaches from the current request.
void	setObject(T object) Manually loads the model with the specified object.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

LoadableDetachableModel

public LoadableDetachableModel()

Construct.

LoadableDetachableModel

public LoadableDetachableModel(T object)

This constructor is used if you already have the object retrieved and want to wrap it with a detachable model.

Parameters:

object - retrieved instance of the detachable object

Method Detail

detach

public void detach()

Description copied from interface: IDetachable

Detaches model after use. This is generally used to null out transient references that can be re-attached later.

Specified by:

detach in interface IDetachable

See Also:

IDetachable.detach()

getObject

public final T getObject()

Note: If load() fails with an exception then null is kept as the attached value. Wicket 7.x improves this by staying detached instead, see WICKET-5772.

Specified by:

getObject in interface IModel<T>

Returns:

The model object

See Also:

IModel.getObject()

isAttached

public final boolean isAttached()

Gets the attached status of this model instance

Returns:

true if the model is attached, false otherwise

toString

public String toString()

Overrides:

toString in class Object

See Also:

Object.toString()

load

protected abstract T load()

Loads and returns the (temporary) model object.

Returns:

the (temporary) model object

onAttach

protected void onAttach()

Attaches to the current request. Implement this method with custom behavior, such as loading the model object.

onDetach

protected void onDetach()

Detaches from the current request. Implement this method with custom behavior, such as setting the model object to null.

setObject

public void setObject(T object)

Manually loads the model with the specified object. Subsequent calls to getObject() will return object until detach() is called.

Specified by:

setObject in interface IModel<T>

Parameters:

object - The object to set into the model