Thanks. I hadn't considered the possibility that this wasn't a managed bean.
So if it's an unmanaged bean, it sounds like it's better to work with
the Map directly, but if it is a managed bean you probably don't want
to do that since the bean may not exist yet.
On 11/18/05, Craig McClanahan <[EMAIL PROTECTED]> wrote:
>
>
> On 11/18/05, Mike Kienenberger <[EMAIL PROTECTED]> wrote:
> > Why is pulling the bean from the session map better than asking the
> > application for it using
> >
> facesContext.getApplication().getVariableResolver().resolveVariable("neededBean")
> > or facesContext.getApplication
> ().createValueBinding("#{neededBean}").getValue(facesContext),
> > which is what Don suggested?
>
> The latter two methods will work *if* the bean already exists, *or* if
> you've defined "user" as a managed bean as well. In that case, it will do
> the normal "create this bean for you if it does not exist" trick, as well as
> looking it up for you.
>
> Using the Map is better if you do *not* want to trigger a managed bean
> creation. But all of these methods are feasible.
>
> > Wouldn't it be possible that a custom variable resolver may not store
> > the bean in the session map under that name?
>
> That would be technically feasible, but it would break the contract for the
> default VariableResolver defined in the spec ... that doesn't seem like
> something you would want to have happen.
>
> > Or perhaps there's some
> > other reason why this might not work in some alternate JSF
> > implementation. It just seems like you're working too close to the
> > internals by reading it out of the map yourself.
>
> Actually, the Map in question is *required* by the spec to act the way it
> does. In fact, it's not a "real" Map at all (in the sense of something like
> HashMap or TreeMap) ... it is an abstraction that, underneath the covers,
> calls session.getAttribute(), session.setAttribute(), and so on. The reason
> a Map representation was chosen was to hide the fact that the underlying
> session object is an HttpSession if you're running in a standard webapp, or
> a PortletSession when you're running in a portlet.
>
> Craig
>
>
