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From Jeff Caddel <jcad...@cox.net>
Subject Re: [Chain] ContextToRequestCommand
Date Mon, 10 Nov 2003 06:44:35 GMT

>If your application uses WebContext (or one of it's subclasses) as the Context
>object being passed down the chain, you already have access to the request
>attributes via the getRequestScope() method.  There's also other Map-returning
>methods on WebContext for lots of other useful stuff (headers, cookies, session
>attributes, context attributes, context init parameters, ...).
>
Ahhhh.  Brain cells starting to click now.  One huge benefit of exposing 
them as map's being that you can make use of generic bean manipulating 
code to mess with them, right?  Instead of making API specific calls 
like getAttribute/setAttribute.

>
>On the attribute collections in particular, the Map implementation is two-way
>... for example, usage like this:
>
>  public boolean execute(Context context) throws Exception {
>    ...
>    WebContext wcontext = (WebContext) context;
>    // Following is equivalent to request.getAttribute("foo")
>    String fooValue = wcontext.getRequestScope().get("foo");
>    // Following is equivalent to request.setAttribute("foo", "bar")
>    wcontext.getRequestScope().put("foo", "bar");
>    ...
>  }
>
Which is better since nothing in this implementation makes a servlet 
specific API call.  If I needed the value "bar" to be present under the 
attribute "foo" in a portlet environment (for example), this command 
could be re-used.

>
>makes a request attribute named "foo" with value "bar" visible to a JSP page (or
>whatever) that will ultimately create the response.
>
If I'm getting this right, I could also place "bar" into the request 
under the attribute "foo" (in an API independent manner, nonetheless) by 
simply configuring a CopyCommand:

<command className="org.apache.commons.chain.generic.CopyCommand" 
toKey="requestScope.foo" from="foo"/>

(Assuming that some other previous bit of logic had placed "bar" into 
the context under the key "foo".)

Holy smokes...how easy is that!!

>
>Does this satisfy the sorts of requirements you were after?
>
Fit's the bill quite nicely, Craig.  Thanks.

>
>Craig
>
>
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>
>  
>



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