Hi,
See http://jakarta.apache.org/tapestry/UsersGuide/state.html. First of
all you have a non-tapestry managed property; I don't know if it is
automatically cleared when the page is returned to the pool.
However, normally a page property is not persisted between requests but
cleared as soon as the page goes back to the pool at the end of the
request. To use session persistence you could do the following:
public abstract class ProductPage extends BasePage {
@Persist("session")
public abstract Product product;
...
}
Note that you make your class abstract and you only need to define an
abstract getter, and tapestry will make the property for you, handle
caching, clearing, etc..
Another way to make this work without using the session is by passing
for example the product id as argument to the listener, Then you don't
need a session. However you will need to requery your object from the
database. This should not be a problem if you use something like
hibernate with ehcache, since it won't generally actually go to the
database but just take the object out of the cache. The most fancy way
to do this is to write your own DataSqueezer which "squeezes" your
product to a product id and unsqueezes it by getting it back from the
database. Then you can actually just pass the Product object as an
argument without it being to heavy. See:
http://wiki.apache.org/jakarta-tapestry/DataSqueezer
for how to write a DataSqueezer.
Hope this helps,
Sebastiaan
Matt Welch wrote:
Forgive the "newbness" of this question, but I'm just curious. Let's say if
have a page class similar to the following:
public class ProductPage extends BasePage{
private Product product
public getProduct(){return product;}
public setProduct(Product product){this.product=product;}
@InjectPage("ExtraProductInfoPage");
public abstract ExtraProductInfoPage getExtraProductInfoPage();
public ExtraProductInfoPage onClickExtraProductInfoLink(){
getExtraProductInfoPage.setProduct(product);
return getExtraProductInforPage();
}
}
Ok, as you can see, I'm attempting to access a page property from within my
listener. the listener is called when someone clicks a DirectLink on the
ProductPage page. I'm guessing that this it is incorrect to access page
properties in this manner, because I'm having sporadic issues with the
product that I'm passing to the next page being null.
First, am I correct in assuming what I'm trying to do here won't work? For
some reason, I thought I had understood that Tapestry used the session to
automatically maintain the page properties between the initial request and
the form submissions or links from the page that had been requested. I
assumed that this meant I could access the page properties from my listener
when it was called.
If this usage is not correct, then is there a way to ensure that I can use
the Product object again in my listener without requerying it from my
database? I suppose I could pass the entire Product object as a parameter to
the DirectLink, but won't that produce a URl that's extremely heavy?
Again, I apologize for what I'm sure is an uninformed question. I searched
the mail archives and wasn't able to discover an answer on my own.
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