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From "Craig R. McClanahan" <craig...@apache.org>
Subject Re: bean: access to the session
Date Wed, 21 Mar 2001 17:20:26 GMT


On Wed, 21 Mar 2001, hunkpapa wrote:

> 
> 
> "Craig R. McClanahan" schrieb:
> 
> > On Fri, 4 Jan 1980, hunkpapa wrote:
> >
> > > Hi,
> > > I've a problem with beans.
> > > I can use a bean with the writeTag and this works out well.
> > >
> > > But how can this bean access the session ?
> > > I want to read values I placed in the session
> > > to use them in the getter methods of the bean.
> > >
> > >
> > >
> >
> > If the bean itself is a String you want to write:
> >
> >         <bean:write name="beanName" scope="session"/>
> >
> > If the bean is an object whose property you want to write:
> >
> >         <bean:write name="customer" property="companyName"
> >                 scope="session"/>
> >
> > In general, most Struts tags that accept a "name" attribute also let you
> > specify a "scope" attribute.
> >
> > Craig McClanahan
> 
> OK,
> How is the source of the bean , if i want access the session ?
> 
> 

Do you mean that you want the JavaBean itself to access the session?  If
so, I'm sorry I misunderstood you previously.

In general, a JavaBean will *not* have direct access to the session, or
any other aspect of the servlet API.  You could pass in the current
session as a method parameter (say, from your Action), but that would
create a dependency that this bean would only work inside a servlet-based
web application.

You probably want to look at why your bean needs access to the session in
the first place.  Usually, this would be because you need access to some
other beans that are stored there.  In such a case, you might consider
refactoring your design so that the relevant beans reference each other
directly.

Let's take one really simple example -- let's say you have a Customer
bean, and an ArrayList of Order beans, as two different session
attributes.  But, in order to display information about an order, you need
a reference to the customer to get the customer's name.

One strategy would be to modify your Order bean method so that it has a
"customer" property:

	public class Order {
	    ...
	    public Customer getCustomer();
	    public void setCustomer(Customer 
	    ...
	}

and, when you are creating the order beans in the first place, be sure you
call setCustomer() at the right times.

If you have done this, you no longer need to access the session from an
Order bean in order to display the customer name.  Instead, you can do
things like this (where "orders" is your ArrayList of orders in the
session):

	<logic:iterate id="order" name="orders" scope="session">
	  Order number is <bean:write name="order" property="orderId"/>
          and customer name is
          <bean:write name="order" property="customer.name"/>
	</logic:iterate>

If this is still not what you are after, why don't you describe your
problem in a little more detail.

Craig



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