I implemented this for spring webflow (http://opensource2.atlassian.com/projects/spring/browse/SWF-9) and now I also implemented it for spring mvc...

maybe it can be included

Objective:
I find in almost all situations that the bulk of work in building a web app is to collect data from varying locations and ultimately construct an object graph that you can then persist or use for querying. This is especially true if using hibernate or another ORM tool.

Conclusion:
The proposed code below accomplishes that so that by the time you get to the action the populated objects would already be pre-populated and waiting for you in the scope you specify. So the action code would then be very simple or non-existent.

Summary:
The current FormAction only allows the creation of one form object per action. My thought is that if using hibernate or another ORM tool what you want instead is multiple objects (one per each domain object) so that at the time you run the action the object graph will already be created and all you need to do is extract it from the context and use it to query or persist. This avoids the bulk of the work generally in actions to assemble domain objects.

So basically this is IoC for a scope object to either create object in scope and set properties, set property on object already in specified scope or add object to collection of an object already in specified scope.


Below is illustration of pattern. I use it in a portlet application but a ServletAttributeResolver can simply be created as well as I did in webflow version...

Here is the idea from the portlet side:

  <bean id="portletModeControllerMapping"
        class="org.springframework.web.portlet.handler.PortletModeHandlerMapping">
    <property name="portletModeMap">
      <map>
        <entry key="view">
          <ref bean="viewModeFrontController" />
        </entry>
      </map>
    </property>
      <property name="interceptors">
         <list>
          <ref bean="topicDetailsRequestDTOInjector"/>
            <ref bean="openSessionInViewInterceptor"/>
         </list>
      </property>

  </bean>

This is the handler of which there is an equivalent handler for dispatcher servlet.

  <bean id="viewModeFrontController"
        class="com.xxx.contactus.spring.mvc.action.ContactUsController">
         <property name="contentPage" value="contactUs.Select.Topic.view"/>
         <property name="contactUsService">
<ref bean="contactUsService"/>
</property>
  </bean>

This is a simple abstract controller...

and here is the injector which is simply a form controller that can be used as an interceptor

<bean id="topicDetailsRequestDTOInjector" class="org.springframework.portlet.mvc.injector.ContextInjector">
    <property name="attributeResolvers">
       <map>
         <entry key="type">
           <bean class="org.springframework.portlet.mvc.injector.PortletAttributeResolverImpl">
             <property name="fromObject" value="application_user.type"/>
             <property name="attributeSourceChain"
                             value="applicationSession"/>
           </bean>
         </entry>
         <entry key="specialty">
           <bean class="org.springframework.portlet.mvc.injector.PortletAttributeResolverImpl">
             <property name="fromObject" value="application_user.specialty"/>
             <property name="attributeSourceChain"
                             value="applicationSession"/>
           </bean>
         </entry>
       </map>
    </property>
<property name="commandName"><value>topicDetailsRequestDTO</value></property>
<property name="commandClass"><value>com.xxx.contactus.dto.TopicDetailsRequestDTO</value></property>
</bean>




I have attached the source. It can be used as is for spring portlet mvc and with a simple adaptation it can be used also for servlet type controllers. I just didn't do it because I am sure you guys will have ideas how to make it better.