com.davesag.jsf
Class AbstractReadWriteHandler

java.lang.Object
  com.davesag.jsf.AbstractContextAwareBean
      com.davesag.jsf.AbstractHandler
          com.davesag.jsf.AbstractReadWriteHandler

All Implemented Interfaces:

Handler, ReadWriteHandler

public abstract class AbstractReadWriteHandler

extends AbstractHandler

implements ReadWriteHandler

The AbstractReadWriteHandler is a base class for you to develop your own handler Managed Beans. To implement a specific ReadWriteHandler for your own data types simply fill in the methods to do the following:

• loadById(Object id) - returns an object, given some unique id.
• instantiateItem- returns a new object
• saveItem - write the object to some underlying persistent store.
• viewToModel - map data from the form fields to the actual object
• modelToView - map data from the handled object to the form fields

ReadWriteHandlers correspond to the controller component of the MVC pattern.

Version:

CVS Revision $Id:$

Field Summary

Fields inherited from class com.davesag.jsf.AbstractHandler

CANCEL, ERROR, SUCCESS, theFields, theItem

Constructor Summary

AbstractReadWriteHandler()

Method Summary

String	create() Makes a new instance of the bean to be handled.
String	delete() deletes the current item.
protected abstract void	deleteItem(Object model) deletes the item from a persistent store.
protected abstract Object	instantiateItem() If permitted, this method should create a new default item.
String	release() releases the current item without saving.
String	save() Saves the item.
protected abstract Object	saveItem(Object model) saves the item to a persistent store.
protected abstract Object	viewToModel(Map view, Object model) populate the supplied object with data from the view's fields map.

Methods inherited from class com.davesag.jsf.AbstractHandler

clear, getFields, getItem, isActive, load, loadById, modelToView, view

Methods inherited from class com.davesag.jsf.AbstractContextAwareBean

addMessage, getContext, getMessageBundleName, getRequestParameter, getServletContext, getSession

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.davesag.jsf.Handler

getFields, getItem, isActive, load

Constructor Detail

AbstractReadWriteHandler

public AbstractReadWriteHandler()

Method Detail

instantiateItem

protected abstract Object instantiateItem()
                                   throws Exception

If permitted, this method should create a new default item. If it can not then return null and be sure that you deal with this situation in viewToModel(java.util.Map, java.lang.Object) and AbstractHandler.modelToView(java.lang.Object, java.util.Map).

Returns:

the instatiated object, or null. If null then the underlying object must be built in the first pass of viewToModel.

Throws:

Exception - if anything bad happens.

saveItem

protected abstract Object saveItem(Object model)

saves the item to a persistent store.

Parameters:

model - The object you wish to save.

Returns:

the saved object.

deleteItem

protected abstract void deleteItem(Object model)
                            throws Exception

deletes the item from a persistent store.

Parameters:

model - The object you wish to delete.

Throws:

Exception - if anything went wrong.

viewToModel

protected abstract Object viewToModel(Map view,
                                      Object model)

populate the supplied object with data from the view's fields map. If the underlying object is null then this may be because the constructor for that object requires some as yet unset properties. In this case you can now construct the object using the values supplied. The need for this could be minimised by correct use of JSF Converters. Thought - should this throw a javax.faces.ConverterException?

Parameters:

view - The map of properties captured from the user interface.

model - The object to populate based on values in the view.

Returns:

the newly populated object, or null if there was a mapping error.

create

public String create()

Makes a new instance of the bean to be handled.

Specified by:

create in interface ReadWriteHandler

Returns:

a result code.

save

public String save()

Saves the item. If it doesn't have an id, then it will get one when it is saved.

Specified by:

save in interface ReadWriteHandler

Returns:

a result code.

release

public String release()

releases the current item without saving. this is an exit point for the handler. after release is called there is no current item.

Specified by:

release in interface ReadWriteHandler

Returns:

a result code.

delete

public String delete()

deletes the current item. this is an exit point for the handler. If there was any error trying to delete the current item then this method will still act as an exit point. In all circumstances after delete is called there is no current item.

Specified by:

delete in interface ReadWriteHandler

Returns:

a result code.