Re: [Actionframework-users] Passing objects from request to another...

[Petr T. <cz5...@ti...>]

Hello again!

><action name=3D"/addObject" method=3D"newObject()">
>  <on-return value=3D"*" assign-to=3D"objectStoreId" show-url=3D"objectU=
RL">
>    <output-variable name=3D"objectURL" 
>                     value=3D"/ActionServlet/editObject/$objectStoreId"/=
>
>  </on-return>
></action>
>
><action name=3D"/getObject/$objectId" method=3D"newobject(String objectI=
d)">
>  <on-return value=3D"*" assign-to=3D"objectStoreId" show-url=3D"objectU=
RL">
>    <output-variable name=3D"objectURL" 
>                     value=3D"/ActionServlet/editObject/$objectSoreId"/>=

>  </on-return>
></action>
>
><action name=3D"/editObject/$objectStoreId" method=3D"getObjectStore(Str=
ing

>objectStoreId)">
>  <on-return value=3D"*" assign-to=3D"object" 
>             show-template=3D"org/visres/ivr/security/view/EditObject.ht=
ml.vm"/>
></action>

>I have also created a seperate ObjectStore class that holds objects in
a
>HashMap and allows entry of objects into the HashMap, returning a unique=

>id for the object just stored, and also a object remove method.  Another=

>point is that I'm only interested in having an object stored while I'm

>on its corresponding add/edit page otherwise there is no need to have it=

>around.
>
>If in our system we choose to add an Object and execute the /addObject

>action, the newObject() method will create a new Object and place it in

>the ObjectStore returning a unique store id.  Now that we have stored a

>new Object the url is redirected to the editObject action which will 
>pull this object out of the ObjectStore.  Much the same happens when 
>editing an object already in the database.  If we execute the 
>/editObject action passing the selected objects database id to the 
>newObject(String objectId) method, the objects values are retrieved from=

>the database and the object is stored returning its unique store id 
>(remember that we will now have two id's for an object one being its 
>actual id in the database and the other its id for the ObjectStore). 
>Again the url will redirect to the /editObject action.

You can use <invoke> element to avoid URL redirecting - example:

<action name=3D"/addObject" method=3D"newObject()">
  <on-return value=3D"*" assign-to=3D"objectStoreId" 
                       show-template=3D"org/visres/.../EditObject.html.vm=
">
    <invoke method=3D"getObjectStore(String objectStoreId)">
       <input-variable name=3D"objectStoreId" value=3D"$objectStoreId"/>
    </invoke>
  </on-return>
</action>

>So if, for example, I wanted to change the /addObject action to use your=

>"optional attribute for <in/output-variable>" idea, then I'd like to 
>totally replace the ObjectStore class, meaning that when I save an 
>object to the session I'd like to get a unique store/session id in 
>return and I'd also like to be able to remove objects from the session.

>I don't think simply adding a scope attribute to the <output-variable>

>tag will provide this functionality.  You could decide that you do not

>want to provide all this functionality apart from adding objects to the

>session and leave the unique id functionality to the developer.  What do=

>you think?

Summary:

1) you need to transfer an object across calls - this can be achieved by:=

   a) storing it in a session component (like your ObjectStore)
   b) putting it into the session directly (by 'scope' attribute)
   c) serializing it in the request/response (clumsy or even impossible)
   d) ?

AS can implement 1b) easily (by ParameterRetriever), the question is:
2) how to remove our object from the session:
   a) let it expire with the session (default behaviour)
   b) remove it from the session when the <in/output-variable> scope chan=
ges
   c) programatically: ctx.get("REQUEST").getSession().removeValue("id")
   d) ?

I think that "id management" should not be done by AS. If you need to pas=
s
both object and its id, you can simply put them as two $variables into th=
e
context/session (or include the id with its object).

>Also, a quick update on other aspects of the framework.  First the issue=

>of show-template/show-url attribute, since being able to pass objects 
>from one request to another things are working really well.  Our 
>implementation is such that the show-template attribute is only ever 
>used once on each template, if another action wants to reach this 
>template then you are forced to call the show-url attribute that 
>redirects to the action that contains the show-template for the template=

>you wish to see.  This ensures that any <output-variable>'s that are 
>required for this template are loaded.  Secondly, I also think we were


Nesting <output-variable>s inside <template> allows all necessary $variab=
les
to be set up for the template.

>possibly trying to do too much with the framework, where when a user 
>updates a particular object and the updates throw errors, we were using

>actually using the <on-exception> tag to catch these errors and take the=

>appropriate action.  I think as far as redirecting to different url's is=

>concerned the framework works really well but when you want to stay on

>the same url and produce some error messages then it's best not to throw=

>this up to ActionServlet but to deal with it in your components.

Can you explain what are you missing or give me a comparing example pleas=
e?

>Sorry for the length of the mail, but if you've understood it that would=

>be good, if you could make some comments/suggestions that would be 
>REALLY good and if you could actually implement some of the ideas that

>would be absolutely AMAZING!!!!   :-)

I'm going to set up Tasks for AS this week. I still don't have much time,=

but I believe I can do some of "the most expected" RFEs :)

-Petr

[ http://dione.zcu.cz/~toman40 - Pet...@pi... - ICQ=3D22957959 ]


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