Because if you implement the methods, you're responsible for
initializing and otherwise dealing with the page properties. If you
leave them abstract Tapestry takes care of all of that for you. You
only have to even declare the abstract methods if you actually call
them in your own Java code, and that's just to make the compiler
happy. Any calls that Tapestry makes internally (to set or get
properties from the page) happen automatically.
It's a little confusing and indirect, but it really does make your
life easier.
HTH,
Todd
On Jun 30, 2005, at 9:22 PM, Vadim Pesochinskiy wrote:
OK. Here is an example of page class that he has. Abstract methods
are getters and setters. Same methods are referenced in
corresponding .page file, also listed below. I am absolutely
clueless as to what would be the reason for leaving this methods
abstract.
I would imagine tapestry will do enhancing to wrap implementations
of setters to know if object has to be stored in session, but why
would you want to leave methods and class abstract and not have
class that implements it?
I am pondering if he uses some code generation to create java beans
that are domain objects used with hibernate, but I do not see any
evidence of that anywhere in the source tree or build files.
package org.apache.tapestry.pets.presentation.pages;
import johnmammen.betterpetshop.service.PetshopManager;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.event.PageEvent;
import org.apache.tapestry.event.PageRenderListener;
import org.apache.tapestry.pets.PetshopBasePage;
import org.apache.tapestry.pets.domain.model.IProduct;
import org.apache.tapestry.pets.presentation.components.PagedModel;
public abstract class CategoryPage extends PetshopBasePage implements
PageRenderListener {
//for getting the petshop service
public abstract PetshopManager getPetshopService();
public void pageBeginRender(PageEvent event) {
if (getModel() == null)
setModel(new PagedModel());
if (getCategory() != null) {
//getting the petshop service
setProductList(getPetshopService().findByCategory
(getCategory()));
}
}
public void selectItem(IRequestCycle cycle) {
Object[] parameters = cycle.getServiceParameters();
String prodid = ((String) parameters[0]);
String prodname = ((String) parameters[1]);
ProductCategoryPage productcategory = (ProductCategoryPage)
cycle
.getPage("ProductCategory");
productcategory.setProdID(prodid);
productcategory.setProdName(prodname);
cycle.activate(productcategory);
}
public void directJumpToPage(IRequestCycle cycle) {
Object[] parameters = cycle.getServiceParameters();
int page = ((Integer) parameters[0]).intValue();
int pCount = ((Integer) parameters[1]).intValue();
setCategory((String) parameters[2]);
PagedModel nmodel = new PagedModel();
nmodel.setPageCount(pCount);
nmodel.setPageToShow(page);
setModel(nmodel);
}
public abstract void setCategory(String value);
public abstract String getCategory();
public abstract void setProductList(IProduct[] productList);
public abstract IProduct[] getProductList();
public abstract int getProductPage();
public abstract void setProductPage(int productPage);
public abstract IProduct getProduct();
public abstract void setProduct(IProduct product);
public abstract PagedModel getModel();
public abstract void setModel(PagedModel model);
}
<?xml version="1.0"?>
<!DOCTYPE page-specification PUBLIC
"-//Apache Software Foundation//Tapestry Specification 3.0//EN"
"http://jakarta.apache.org/tapestry/dtd/Tapestry_3_0.dtd";>
<page-specification
class="org.apache.tapestry.pets.presentation.pages.CategoryPage">
<property-specification name="category" type="java.lang.String"/>
<property-specification name="product"
type="org.apache.tapestry.pets.domain.model.IProduct"/>
<property-specification name="productList"
type="org.apache.tapestry.pets.domain.model.IProduct[]"/>
<property-specification name="productPage" type="int"/>
<property-specification name="model"
type="org.apache.tapestry.pets.presentation.components.PagedModel"/>
<property-specification name="petshopService"
type="johnmammen.betterpetshop.service.PetshopManager">
global.appContext.getBean("petshopService")
</property-specification>
</page-specification>
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