Adam Hardy wrote:
Adam Hardy on 01/05/08 13:51, wrote:
Jeromy Evans on 01/05/08 12:48, wrote:
Adam Hardy wrote:
I have been casting around for a while for the most elegant and
quick-to-code mechanism for putting populating lists for select
controls.
I wanted to run this one idea past the struts users to get any
feedback on something I may have missed or need to know.
One requirement I set myself is that I want to avoid coding for the
dropdown lists in every action method.
The Preparable action interface seems ideally suited for this
situation.
I can write a prepare() method and use its MethodFilterInterceptor
to turn it on only when doing reads. My creates, saves and deletes
don't need lists because they do Post-Redirect-Gets back to the
appropriate read.
The reason I ask is that the struts docs make clear that Preparable
is intended for use in param and model management. Is anyone else
using Preparable to do other stuff like this?
I've been toying with the idea of creating a custom interceptor to
do this. It would be effectively the same as you describe, except
that it would inspect the action for the presence of some interface,
annotation, or method, and examine the request for some
characteristic (eg. get method) and if matched it creates/looks up
the model and injects it into an appropriate scope (eg. into the
action, into the action context, request scope, or onto the
valuestack).
That way you could remove all the boilerplate from your actions.
eg, If it placed the model into the actioncontext you could
potentially use
<s:select name="state" list="#states"/>
without your action providing the list or getter at all (except
something must instruct the interceptor to load it).
Just some ideas.
I thought about putting it all in the interceptor but I think it
could get unwieldy once the application grows.
Plus, there may be logic in the list call to restrict the list in
some way. I guess you could do that in an interceptor by casting your
action to what you know it is and then calling the required methods
on your model.
My boiler plate code isn't so bad, and in fact the only boiler plate
stuff is the catch block.
By the way, how would you figure out what the method being called is?
Hard-code a call to fetch anything prefixed "method:" from the HTTP
params? Or is there something on the Struts API already?
Is there an easier way?
String method =
ServletActionContext.getActionContext(request).getActionInvocation().getProxy().getMethod();
That's the right place. It's available as an argument in the
intercetpor. PrepareInterceptor is doing exactly that when it looks for
the presence of the Preparable interface on your action, and then for a
methods matching the prepare<methodName>() signature.
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