Package org.apache.wicket.model

Class LoadableDetachableModel<T>

java.lang.Object
org.apache.wicket.model.LoadableDetachableModel<T>
Type Parameters:
T - The Model Object type
All Implemented Interfaces:
Serializable, IDetachable, IModel<T>, IClusterable
Direct Known Subclasses:
StringResourceModel
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:

  • Constructor Details

    • LoadableDetachableModel

      public LoadableDetachableModel()
      Default constructor, constructs the model in detached state with no data associated with the model.

    • 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. Constructs the model in attached state. Calls to getObject() will return object until detach() is called.
      Parameters:
      object - retrieved instance of the detachable object

  • Method Details

    • 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
      Specified by:
      detach in interface IModel<T>

    • getObject

      public final T getObject()
      Description copied from interface: IModel
      Gets the model object.
      Specified by:
      getObject in interface IModel<T>
      Returns:
      The model object

    • 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

    • 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

    • of

      public static <T> LoadableDetachableModel<T> of(org.danekja.java.util.function.serializable.SerializableSupplier<T> getter)
      Create a LoadableDetachableModel for the given supplier.
      Type Parameters:
      T -
      Parameters:
      getter - Used for the getObject() method.
      Returns:
      the model