Re: [Springframework-developer] About MVC

[<jue...@we...>]

Darren,

I don't know if you've noticed that I've added a related feature =
yesterday: AbstractView has now not  only the standard =
setAttributes(Properties) and setAttributesCSV(String) but also =
setAttributesMap(Map). The latter allows not only for String values but =
also for refs, lists, maps, and props as static model attributes.

To make refs work, I've reworked XmlViewResolver and =
ResourceBundleViewResolver to create their view bean factories as =
children of the surrounding application context. Else, you would not be =
able to reference beans in the application context from view =
definitions.

To not put beans themselves as static attributes into the model but =
rather other objects, maybe use a FactoryBean that returns the model =
attribute? The name of the attribute would be determined by the map key =
in the view definition then. It might still make sense to support a =
special ModelReference bean that creates a whole map of attribute =
key/value pairs.

And BTW, <ref external=3D"..."/> is somewhat deprecated as there is no =
strict check for just referencing external beans. <ref bean=3D"..."/> is =
now the generic one that can reference any bean in any reachable =
context, while <ref local=3D"..."/> can just reference local beans in =
the same XML file (via XML ids).

Juergen


-----Original Message-----
From: spr...@li...
[mailto:spr...@li...]On Behalf
Of Darren Davison
Sent: Wednesday, November 12, 2003 2:50 AM
To: spr...@li...
Subject: [[W3-SPAM]] - Re: [Springframework-developer] About MVC - Email
found in subject


On Tuesday 11 November 2003 23:27, Darren Davison wrote:

> Is there something already in Spring MVC that lends itself to this =
kind
> of behaviour?

without really thinking this through much (since it's gone 1:30am and I =
have=20
to be up again in 4 hours)..

If an interface..

public interface ModelReference {
    public Map getModel();
}

.. is implemented by some arbitrary business objects, then a view could =
be=20
defined as..

<bean id=3D"myVelocityView"
  class=3D"org.springframework.web.servlet.view.velocity.VelocityView">
  <property name=3D"templateName"><value>main.vm</value></property>  =20
  <!-- standard attribs -->
  <property name=3D"attributes">
    <props>
      <prop key=3D"title">A Velocity Page</prop>
    </props>
  </property> =20

  <!-- new property: list of ModelReference implementing bus. objects =
-->
  <property name=3D"references">
    <list>
      <ref external=3D"myBean"/>
      <ref external=3D"myOtherBean"/>
    </list>
  </property>          =20
</bean>


AbstractView is amended with the following (part pseudo-code)..

public abstract class AbstractView extends WebApplicationObjectSupport=20
implements View {

  //added
  private Map referenceObjects =3D new HashMap();

  ...

  //added
  public final void setReferencesList(List references) {   =20
    for each list item
      get bean from app context if exists
      if bean instanceof ModelReference=20
        call bean.getModel()=20
        consolidate into referenceObjects field
      end
    end
  }

  //amended
  public final void render(Map model, HttpServletRequest request,=20
HttpServletResponse response)
 =20
    ...
    Map mergedModel =3D new HashMap(this.staticAttributes);
    mergedModel.putAll(referenceObjects);
    mergedModel.putAll(model);
    ...
  }

}


 - The controller still has final say and can overwrite model values =
from=20
the static list or the reference list

 - Arbitrary beans can now add to the model that a view renders on a per =

view basis taking advantage of whatever container resources or custom =
logic=20
is required

 - multiple views can use the same ref objects via the hierarchical view =

structure

 - It's a kind of half-way house between static attributes and model =
data=20
returned by the controller but as shown isn't parameterised so =
reasonably=20
rigid

 - maybe the interface can be dropped and the actual method to call for =
any=20
given bean can be specified in the config too.  One less dependency for =
the=20
business object


Goodnight.


--=20

Darren Davison
Public Key: http://www.davison.uk.net/key.jsp



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