Re: Question concerning struts-config and app constants

[Erik Weber]

D'oh! This from 
http://struts.apache.org/api/org/apache/struts/actions/MappingDispatchAction.html

"Also, a request parameter, which would be visible to the application 
user, is not required to enable selection of the handler method."

Looked right at that and didn't see it!
Thanks again,
Erik

Jim Barrows wrote:
-----Original Message-----
From: Erik Weber [mailto:[EMAIL PROTECTED]
Sent: Wednesday, July 14, 2004 4:15 PM
To: Struts Users Mailing List
Subject: Re: Question concerning struts-config and app constants
Thanks Joe, that is indeed what I am doing. I am handling a 
few actions 
in a single Action class, but parameterizing on my own rather 
than using 
the MappingDispatchAction. The reason is that the O'Reilly 
Struts book 
led me to believe that if you want to use the DispatchAction 
class, or 
the LookupDispatchAction class, you have to put the "method" 
parameter 
into your requests. Please correct me if that is wrong. But I 
don't like 
that. Is the MappingDispatchAction different from those (my 
book doesn't 
seem to cover it)? I prefer to use a switch (the if-else block you 
describe), to the chagrin of the OO purists, if it means I 
can keep the 
   

Well.... from the javadocs for public class MappingDispatchAction:
To configure the use of this action in your struts-config.xml file, create an entry 
like this:
  <action path="/saveSubscription"
          type="org.example.SubscriptionAction"
          name="subscriptionForm"
         scope="request"
         input="/subscription.jsp"
     parameter="method"/>
where 'method' is the name of a method in your subclass of MappingDispatchAction that 
has the same signature (other than method name) of the standard Action.execute method.
Nothing in the there about the URL....  so yes you could use it for what you want to.  
You can look at the javadocs yourself and see a better example of how it works.


 

URLs the user sees looking the way I want (I never much liked query 
strings). My Action classes are not so course-grained as to 
become error 
prone -- my parameter values are the likes of "add", "update" 
and "delete".

What do you think?
Thanks,
Erik
Joe Germuska wrote:
   

> I am parameterizing an Action via the "parameter" 
       

attribute to the
   

action element in struts-config.xml. The Java code in 
         

the Action class
   

refers to the possible parameter values using String 
         

constants instead
   

of using literal values. However, these same parameter 
         

values are 
   

simply
hardcoded in struts-config.xml. So if I change the values of the
constants, I have to change struts-config.xml, and 
         

vice-versa. Is 
   

there
         

> an easy way to have the values for these constants in one place?
       

If you describe somewhat more what you're doing with the parameters 
inside the action, we might be able to suggest an alternative 
implementation.  For example, if you're doing some kind of 
     

conditional 
   

checking:
if (MY_CONSTANT1.equals(mapping.getParameter())) { ... }
else if (MY_CONSTANT2.equals(mapping.getParameter())) { ... }
you might instead be able to use the MappingDispatchAction, which 
would encode the Java side of your values as method names 
     

instead of 
   

as String constants and eliminate the need to test the parameter 
against the constant.

     

http://struts.apache.org/api/org/apache/struts/actions/MappingDispatchAction.html 
 

Joe
   

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