[OT] scope trick

[Dennis Byrne <de...@dbyrne.net>]

The spec says higher scoped managed beans cannot be injected into lower scoped managed beans.  This doesn't mean we can't inject session scoped data into request scope managed beans ...

<managed-bean>
 <managed-bean-name>geographyProducer</managed-bean-name>
 <managed-bean-class>gov.blm.ak.GeographyConsumerThread</managed-bean-class>
 <managed-bean-scope>request</managed-bean-scope>   
  <managed-property>
    <property-name>sharedData</property-name>
    <value>#{facesContext.externalContext.sessionMap['sharedData']}</value>
  </managed-property>
</managed-bean>

Dennis Byrne

Re: [OT] scope trick

[Craig McClanahan <cr...@apache.org>]

On 6/1/06, Dennis Byrne <de...@dbyrne.net> wrote:
>
> The spec says higher scoped managed beans cannot be injected into lower
> scoped managed beans.  This doesn't mean we can't inject session scoped data
> into request scope managed beans ...
>
> <managed-bean>
> <managed-bean-name>geographyProducer</managed-bean-name>
> <managed-bean-class>gov.blm.ak.GeographyConsumerThread
> </managed-bean-class>
> <managed-bean-scope>request</managed-bean-scope>
>   <managed-property>
>     <property-name>sharedData</property-name>
>     <value>#{facesContext.externalContext.sessionMap
> ['sharedData']}</value>
>   </managed-property>
> </managed-bean>


I had to read your double negative three times before I think I got it :-)

Yes, you can do this ... but you are working too hard with that kind of an
expression.  Try this instead:

    <value>#{sharedData}</value>

As long as you don't also have a "sharedData" bean in request scope, this
will pick up the session scoped bean for you (and also create it if
necessary, if it is a managed bean).

Dennis Byrne


Craig

Re: [OT] scope trick

[Ondrej Svetlik <on...@svetlik.info>]

Dennis Byrne wrote:
> The spec says higher scoped managed beans cannot be injected into lower scoped managed beans.  This doesn't mean we can't inject session scoped data into request scope managed beans ...
> 
> <managed-bean>
>  <managed-bean-name>geographyProducer</managed-bean-name>
>  <managed-bean-class>gov.blm.ak.GeographyConsumerThread</managed-bean-class>
>  <managed-bean-scope>request</managed-bean-scope>   
>   <managed-property>
>     <property-name>sharedData</property-name>
>     <value>#{facesContext.externalContext.sessionMap['sharedData']}</value>
>   </managed-property>
> </managed-bean>
> 
> Dennis Byrne
> 

Well, in my opinion, this is exactly what the spec says.

http://wiki.apache.org/myfaces/AccessingOneManagedBeanFromAnother

<cite>
The constraints are that:

  * the using bean must have scope which is the same as or shorter than 
the needed bean
  * the using bean must have a property-setter method which takes the 
needed bean as a parameter
  * the beans cannot have managed dependencies on each other.
</cite>

In your example geographyProducer is the using bean and has shorter 
scope (request) than the session scoped bean, whatever way you use to 
access it.

Best regards

Ondrej Svetlik