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Posted to user@struts.apache.org by Bill Firestone <bi...@cisco.com> on 2001/06/18 19:26:25 UTC

RE: No ActionForm Bean Required

I have hit upon the same problem as this thread, but I didn't see a resolution.

It seems that in Struts 1.0, there must be an ActionForm for every page that has a form in it -- or, indeed, an ActionForm for every form, including one for each form on a page.  

I had thought that I could have an Action class that would read the FORM parameters directly, but that I would not need an ActionForm for each screen.  

(One of the goals for Struts 1.1 seems to address this.)

Is the above correct, or am I missing something?

Thanks.

Bill Firestone

At 03:09 PM 4/30/2001 +0530, Tewathia, Atul wrote:
>I feel there is some problem.
>I tried the same thing but I get the following error on console. It shows
>that it is trying to instantiate a form bean corresponding to an action
>mapping. And if i am not specifying one it gives an error. How do I handle
>this situation when I don't need a form ???
>
>OneForm instantiated
>TwoaeForm instantiated
>TwokeyForm instantiated
><Apr 13, 2001 2:54:59 PM GMT+05:30> <Error> <HTTP>
><[WebAppServletContext(446938
>,threeoseven)] Root cause of ServletException
>javax.servlet.jsp.JspException: Cannot retrieve definition for form bean
>null
>        at org.apache.struts.taglib.html.FormTag.lookup(FormTag.java:725)
>        at
>org.apache.struts.taglib.html.FormTag.doStartTag(FormTag.java:441)
>        at jsp_servlet._two._jspService(_two.java:345)
>        at weblogic.servlet.jsp.JspBase.service(JspBase.java:27)
>        at
>weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm
>
>the config.xml used by me is here ...
>
><struts-config>
>  <form-beans>
>    <form-bean name="oneForm" type="org.apache.struts.myprog.OneForm"/>
>    <form-bean name="twokeyForm"
>type="org.apache.struts.myprog.TwokeyForm"/>
>    <form-bean name="twoaeForm" type="org.apache.struts.myprog.TwoaeForm"/>
>  </form-beans>
>  <action-mappings>
>    <action path="/One" type="org.apache.struts.myprog.OneAction"
>name="oneForm">
>        <forward name="Two" path="/Two.jsp" />
>    </action>
>    <action path="/Twoae" type="org.apache.struts.myprog.TwoAction"
>name="twoaeForm">
>        <forward name="Three" path="/Three.jsp" />
>    </action>
>    <action path="/Twokey" type="org.apache.struts.myprog.TwoAction"
>name="twokeyForm">
>        <forward name="Three" path="/Three.jsp" />
>    </action>
>    <action path="/Twoprev" type="org.apache.struts.myprog.TwoAction">
>        <forward name="One" path="/One.jsp" />
>    </action>
>  </action-mappings>
></struts-config>
>
>
>-----Original Message-----
>From: Tobias Meyer [mailto:t-g-p@gmx.de]
>Sent: Wednesday, April 18, 2001 4:17 PM
>To: struts-user@jakarta.apache.org
>Subject: RE: No ActionForm Bean Required
>
>
>Hi Stanley,
>
>> Let's say I have a link that allows a user to empty his/her shopping
>> cart.  The link to empty the cart points to "/empty.do".  I
>> do not believe
>> this requires an ActionForm bean (PLEASE, correct me if I am
>> wrong).  Nonetheless, I have specified an ActionForm Bean
>> because it is
>> required:
>>
>>      <action path="/empty"
>>              type="EmptyAction"
>>              name="buyBean"
>>              scope="request">
>>          <forward name="success" path="/viewcart.jsp"/>
>>      </action>
>>
>> The bean is NOT used and has nothing to do with emptying the shopping
>> cart.  Do I just accept that it works?  Or am I designing the program
>> wrong?  Please help.
>
>You don't have to specifiy an ActionForm if you don't need one.
>Watch the LogoffAction in the example shipped with struts:
>
><!-- Process a user logoff -->
><action path="/logoff"
>        type="org.apache.struts.example.LogoffAction">
>        <forward name="success"              path="/index.jsp"/>
></action>
>
>Hope this helps,
>
>Tobias Meyer

Re: No ActionForm Bean Required

Posted by Scott Fauerbach <sc...@arondight.com>.

Remember that the struts controller is a servlet?

Did you know that
  javax.servlet.http.HttpServletRequest
implements
   public java.lang.String getParameter(java.lang.String name)

( This is how we used to get the parameters from a form in the olden days.
[last year!] )

The struts perform method:

    public ActionForward perform (ActionMapping mapping,
            ActionForm form,
            HttpServletRequest request,
            HttpServletResponse response) throws IOException,
ServletException {

kindly passes the request to you, for just these type of situations.
Personally, I would go through the effort of using the struts forms.

Scott Fauerbach


----- Original Message -----
From: "Bill Firestone" <bi...@cisco.com>
To: <st...@jakarta.apache.org>
Cc: <st...@jakarta.apache.org>
Sent: Monday, June 18, 2001 10:26 AM
Subject: RE: No ActionForm Bean Required


> I have hit upon the same problem as this thread, but I didn't see a
resolution.
>
> It seems that in Struts 1.0, there must be an ActionForm for every page
that has a form in it -- or, indeed, an ActionForm for every form, including
one for each form on a page.
>
> I had thought that I could have an Action class that would read the FORM
parameters directly, but that I would not need an ActionForm for each
screen.
>
> (One of the goals for Struts 1.1 seems to address this.)
>
> Is the above correct, or am I missing something?
>
> Thanks.
>
> Bill Firestone
>
> At 03:09 PM 4/30/2001 +0530, Tewathia, Atul wrote:
> >I feel there is some problem.
> >I tried the same thing but I get the following error on console. It shows
> >that it is trying to instantiate a form bean corresponding to an action
> >mapping. And if i am not specifying one it gives an error. How do I
handle
> >this situation when I don't need a form ???
> >
> >OneForm instantiated
> >TwoaeForm instantiated
> >TwokeyForm instantiated
> ><Apr 13, 2001 2:54:59 PM GMT+05:30> <Error> <HTTP>
> ><[WebAppServletContext(446938
> >,threeoseven)] Root cause of ServletException
> >javax.servlet.jsp.JspException: Cannot retrieve definition for form bean
> >null
> >        at org.apache.struts.taglib.html.FormTag.lookup(FormTag.java:725)
> >        at
> >org.apache.struts.taglib.html.FormTag.doStartTag(FormTag.java:441)
> >        at jsp_servlet._two._jspService(_two.java:345)
> >        at weblogic.servlet.jsp.JspBase.service(JspBase.java:27)
> >        at
> >weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubIm
> >
> >the config.xml used by me is here ...
> >
> ><struts-config>
> >  <form-beans>
> >    <form-bean name="oneForm" type="org.apache.struts.myprog.OneForm"/>
> >    <form-bean name="twokeyForm"
> >type="org.apache.struts.myprog.TwokeyForm"/>
> >    <form-bean name="twoaeForm"
type="org.apache.struts.myprog.TwoaeForm"/>
> >  </form-beans>
> >  <action-mappings>
> >    <action path="/One" type="org.apache.struts.myprog.OneAction"
> >name="oneForm">
> >        <forward name="Two" path="/Two.jsp" />
> >    </action>
> >    <action path="/Twoae" type="org.apache.struts.myprog.TwoAction"
> >name="twoaeForm">
> >        <forward name="Three" path="/Three.jsp" />
> >    </action>
> >    <action path="/Twokey" type="org.apache.struts.myprog.TwoAction"
> >name="twokeyForm">
> >        <forward name="Three" path="/Three.jsp" />
> >    </action>
> >    <action path="/Twoprev" type="org.apache.struts.myprog.TwoAction">
> >        <forward name="One" path="/One.jsp" />
> >    </action>
> >  </action-mappings>
> ></struts-config>
> >
> >
> >-----Original Message-----
> >From: Tobias Meyer [mailto:t-g-p@gmx.de]
> >Sent: Wednesday, April 18, 2001 4:17 PM
> >To: struts-user@jakarta.apache.org
> >Subject: RE: No ActionForm Bean Required
> >
> >
> >Hi Stanley,
> >
> >> Let's say I have a link that allows a user to empty his/her shopping
> >> cart.  The link to empty the cart points to "/empty.do".  I
> >> do not believe
> >> this requires an ActionForm bean (PLEASE, correct me if I am
> >> wrong).  Nonetheless, I have specified an ActionForm Bean
> >> because it is
> >> required:
> >>
> >>      <action path="/empty"
> >>              type="EmptyAction"
> >>              name="buyBean"
> >>              scope="request">
> >>          <forward name="success" path="/viewcart.jsp"/>
> >>      </action>
> >>
> >> The bean is NOT used and has nothing to do with emptying the shopping
> >> cart.  Do I just accept that it works?  Or am I designing the program
> >> wrong?  Please help.
> >
> >You don't have to specifiy an ActionForm if you don't need one.
> >Watch the LogoffAction in the example shipped with struts:
> >
> ><!-- Process a user logoff -->
> ><action path="/logoff"
> >        type="org.apache.struts.example.LogoffAction">
> >        <forward name="success"              path="/index.jsp"/>
> ></action>
> >
> >Hope this helps,
> >
> >Tobias Meyer
>

Re: Workflow: Struts inside of Struts

Posted by Dan Connelly <ds...@adelphia.net>.

Craig McC. wrote, concerning attempts to concoct a new scope for workflow across multiple applications:
For the first, the servlet spec is not going to help you much. It has
very little to say about cross-application support. ...... The standard
advice is to use databases or EJBs for data that needs to be available
across web applications.

Not quite. It seems to me that there is at least one other interesting avenue by which a cross-application context may be created: HTML scraping. That is, the Struts Controller (given some chained-in Action parsers) can hook hard data from the data stream of a URL connection. The data comes from a second application. There are no shared databases or EJBs between the two applications. Just some AI-ish good sense in the Action servlet.

Ok, "scraping" idea is crude and ad hoc. But soon we will have the exact technologies, SOAP and Web Services, in widespread use. SOAP will pump hard data, client-server style, over URL connections. Someday, http will be just the obligatory eye candy for the XML-challenged client agent. Yes, the web will have EJBs and SQLs for applications that are explicitly created to share within some narrow realm. However, URLs will rule (as they do now) as the lingua franca.

At any rate, that is the way my workflow project is running. (See old post, below.) The applicaions I want to have running with the workflow do not use a shared database or EJBs. My rules say that I can't change the applications.

In Struts Inside of Struts the browser doesn't invoke the inner app, it gets the Struts Action Controller to do the invocation, using a URL connection. Struts Inside of Struts?? Well, the inner app doesn't really need to be Struts. It just needs to be reasonable HTML text.

Maybe I should just call this approaoch Scraping Inside of Struts. Eventually it could be Soap Inside of Struts.

My WFContext, mentioned below, was a bad idea. The session scope of the outer app works just fine. Or, Ted's Hashtable, if you prefer.

----- Original Message -----
From: Dan Connelly
To: struts-dev@jakarta.apache.org
Sent: Tuesday, June 19, 2001 2:52 AM
Subject: Workflow: Struts inside of Struts

For the sake of our discussion on Struts & Workflow, below is most of an internal company proposal from me to a co-worker concerning a simple Workflow demo. This proposal is drawn, in part, from recent ideas posted to this list. What may be different in what I am suggesting is that Workflow really means the "composition" of existing applications. That is, an application that wraps up some number of existing apps. The "View" might be a Todo list in one window in a frameset spawning links to display in the "main" window of the frameset.. Struts inside of Struts.

Dan Connelly

Keeping [our] Workflow extremely simple at this point, it seems
to me that our next step is to show that we can interpose a
"pre-condition" between two separate, pre-exisiting applications. Also,
that we can wrap the two applications in pre- and post- actions.

We have two interesting applications from Apache running on our Tomcat
server: "Mail Accounts" (aka "example") and "File Upload" (aka
"upload). The default setup for these two applications is to run them
in two separate Web Contexts within the server. Currently, there is no
interaction between these two applications. They are just separate
demonstrations of "Struts," the MVC framework (Release 1.0) from Apache.

I propose that we will now develop a Workflow Context (WFContext) to
require that a user wanting to run "File Upload" must first "login"
through the "Mail Accounts" applications and that there must be listed
a "notification account" among that user's email accounts. This is the
Workflow pre-condition to be demonstrated.

Once this pre-condition is satisfied, then the user may proceed to use
"File Upload" to transfer data. For each file transferred, an email
notification of the upload completion status will be sent to the
designated account. This is the Workflow post-action to be
demonstrated. (There will also be pre-actions, but they will be
hidden.)

The aim here is to subsume two existing applications into a new "Upload
with Mail Workflow" application which will control these apps out of its
own Web Context.

(The Web Context is a server concept, while the WFContext is part of the
Workflow logic framework, unknown to Web server. In a previous email I
described a WFContext as an application specific data structure --
principally a hashtable -- that gradually instantiates unknown data in a
controlled manner.)

Our goal is to utilize the logic of the existing applications without
modification to their Java code or to any existing database. It will
be permitted, however, to modify the code of the Struts framework and to
modify the "struts-config.xml" for both of the affected application.
Despite these changes and despite the new Workflow logic (application),
the two applications should continue to run with unchanged
functionality.

It is assumed that Tomcat's security settings would prevent the direct
use of the two applications once the Workflow became a requirement.
Privileged "LDAP" accounts would continue to have direct access to the
two separate applications.

Workflow: Struts inside of Struts

Posted by Dan Connelly <ds...@adelphia.net>.

Dan Connelly

The aim here is to subsume two existing applications into a new "Upload
with Mail Workflow" application which will control these apps out of its
own Web Context.