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Posted to user@struts.apache.org by Caroline Jen <ji...@yahoo.com> on 2003/11/06 08:26:05 UTC
FAQ (Passing Variables Between Actions); But, Stuck and Need Help
Passing variables from one action to another is a
frequently asked question. The answer is to use
either hidden fields or a session object.
The story starts with searching the database. My
application offers options to search the database by
author, title of the article, article ID, or ..... I
have a drop-down list in my JSP for visitors to make a
selection. By clicking on one of those options, the
property "dispatch" is set. And the visitor fills out
the text field to set "keyValue". With both
"dispatch" and keyValue forwarded to an "action"; say,
Action ONE, the desired articles can be retrieved from
the database. So far so good.
What I have handled next is the "author's page" of the
web site. An author can only view his own articles
and perform update, delete, save, ... functions. I
use the hidden field technique to handle it. The
property "dispatch" is arbitrarily set as "author"
(needless to say) and keyValue can be obtained by
String username = request.getRemoteUser();
And,
<html:hidden property="dispatch" value="author"/>
<html:hidden property="keyValue"
value="<%=username%>"/>
are forwarded to the same action (Action ONE) for
processing. Again, no problem.
Now, the application has another user case - editors.
An editor only retrieve and view all articles in
his/her own field of specialization. I arbitrarily
set "dispatch" as "field_of_specialization" and use
the hidden field technique:
<html:hidden property="dispatch"
value="field_of_Specialization"/>
Nonetheless, the way to get the "value" the editor's
field of specialization is from the database. Because
editors are registered members of the web site, the
application should be able to look for his/her profile
and obtain his/her field of specialization in the
database once an editor successfully logs into the web
site. Therefore, it takes an "action" (Action TWO)
that tells the business tier to find the "keyValue" in
the database. And should I put the "keyValue" in a
session object.
I have tried to handle this situation again and again
in many different ways. I am very frustrated and need
help -- how does a user go from by clicking a button
in a JSP to go to Action TWO (get the keyValue) and
then forward this keyValue and
<html:hidden property="dispatch"
value="field_of_Specialization"/>
to Action ONE for retrieving the desired articles from
the database?
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Re: FAQ (Passing Variables Between Actions); But, Stuck and Need
Help
Posted by Adam Hardy <ah...@cyberspaceroad.com>.
On 11/06/2003 09:02 PM Caroline Jen wrote:
> I think I am going for the first method that you
> suggested - create a user bean and store it in a
> session object at login. My concern is that I use
> container managed authentication at login. After the
> container does its job, is there any way other than
> using an Action that delegates the business tier to
> search the database and obtain the value of
> field_of_specialization? If an action has to be
> involved at this point to form a session object, does
> it suffer the the disadvantage of being overwritten if
> the user has more than one browser window opened?
If you include a method call in all your actions to check whether the
user is logged in, and then whether the session bean exists already, you
can determine whether to create the bean or not each time. This won't be
affected by the number of browser windows open, since you will only
create the user bean once.
> at the problem - I provide a buttion in editor's
> page, which is a JSP tile:
>
> <req:isUserInRole role="editor">
> <html:form action="/do/editor/Category">
> <html:submit>View Articles</html:submit>
> </html:form>
> </req:isUserInRole>
>
> If the button is clicked, I attempt to use an Action
> (via the path /editor/Category) to search the database
> for the field_of_specialization. However, I got this
> message in the browser:
>
> [ServletException in:/article/content/menu.jsp] Cannot
> retrieve mapping for action /do/editor/Category'
>
> and in my struts-config.xml
>
> <action
> path="/editor/Category"
> type="org.apache.artimus.article.EditorViewAction">
> <forward
> name="success"
> path="/menu/Find"/>
> </action>
Sorry but I can't see why that problem should occur from the info you
give. Maybe if you start a new thread with a relevant subject title for
this then somebody may be able to help. If you could specify exactly
when or which page causes the error, it might help too.
Adam
--
struts 1.1 + tomcat 5.0.12 + java 1.4.2
Linux 2.4.20 RH9
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Re: FAQ (Passing Variables Between Actions); But, Stuck and Need Help
Posted by Caroline Jen <ji...@yahoo.com>.
Thank you for the very useful and constructive
feedbacks.
I think I am going for the first method that you
suggested - create a user bean and store it in a
session object at login. My concern is that I use
container managed authentication at login. After the
container does its job, is there any way other than
using an Action that delegates the business tier to
search the database and obtain the value of
field_of_specialization? If an action has to be
involved at this point to form a session object, does
it suffer the the disadvantage of being overwritten if
the user has more than one browser window opened?
In regard to the two-action approach that you
discussed toward the end of your message, I
encountered some problems. If you would take a look
at the problem - I provide a buttion in editor's
page, which is a JSP tile:
<req:isUserInRole role="editor">
<html:form action="/do/editor/Category">
<html:submit>View Articles</html:submit>
</html:form>
</req:isUserInRole>
If the button is clicked, I attempt to use an Action
(via the path /editor/Category) to search the database
for the field_of_specialization. However, I got this
message in the browser:
[ServletException in:/article/content/menu.jsp] Cannot
retrieve mapping for action /do/editor/Category'
and in my struts-config.xml
<action
path="/editor/Category"
type="org.apache.artimus.article.EditorViewAction">
<forward
name="success"
path="/menu/Find"/>
</action>
-Caroline
--- Adam Hardy <ah...@cyberspaceroad.com>
wrote:
> On 11/06/2003 08:26 AM Caroline Jen wrote:
> > Passing variables from one action to another is a
> > frequently asked question. The answer is to use
> > either hidden fields or a session object.
> >
> [snip...]
> > Now, the application has another user case -
> editors.
> > An editor only retrieve and view all articles in
> > his/her own field of specialization. I
> arbitrarily
> > set "dispatch" as "field_of_specialization" and
> use
> > the hidden field technique:
> >
> > <html:hidden property="dispatch"
> > value="field_of_Specialization"/>
> >
> > Nonetheless, the way to get the "value" the
> editor's
> > field of specialization is from the database.
> Because
> > editors are registered members of the web site,
> the
> > application should be able to look for his/her
> profile
> > and obtain his/her field of specialization in the
> > database once an editor successfully logs into the
> web
> > site. Therefore, it takes an "action" (Action
> TWO)
> > that tells the business tier to find the
> "keyValue" in
> > the database. And should I put the "keyValue" in
> a
> > session object.
>
> One method that I use is to create a user bean and
> store that in the
> session at login. This bean could include your
> editor's field of
> specialization, so that you don't need an extra
> action.
>
> Secondly, you could drop the Action One by
> incorporating the field of
> specialization as a part of one SQL statement, so
> that you never
> actually extract the field of specialization from
> the DB. I.e. something
> like this:
>
> SELECT article_title, article_text FROM app_user,
> article
> WHERE app_user.user_name = ?
> AND app_user.field_of_specialization =
> article.field_of_specialization
>
> Alternatively if you still want to do 2 actions, I
> have seen people
> handle it in various ways: (1) get the
> action-forward in your action and
> modify the path to add a query_string with your
> keyValue on it (2) put
> the keyValue in a cookie (3) as you said, put it in
> the session. 2 & 3
> have the disadvantage that they could be overwritten
> if the user has
> more than one browser window open.
>
> HTH
> Adam
>
> --
> struts 1.1 + tomcat 5.0.12 + java 1.4.2
> Linux 2.4.20 RH9
>
>
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Re: FAQ (Passing Variables Between Actions); But, Stuck and Need
Help
Posted by Adam Hardy <ah...@cyberspaceroad.com>.
On 11/06/2003 08:26 AM Caroline Jen wrote:
> Passing variables from one action to another is a
> frequently asked question. The answer is to use
> either hidden fields or a session object.
>
[snip...]
> Now, the application has another user case - editors.
> An editor only retrieve and view all articles in
> his/her own field of specialization. I arbitrarily
> set "dispatch" as "field_of_specialization" and use
> the hidden field technique:
>
> <html:hidden property="dispatch"
> value="field_of_Specialization"/>
>
> Nonetheless, the way to get the "value" the editor's
> field of specialization is from the database. Because
> editors are registered members of the web site, the
> application should be able to look for his/her profile
> and obtain his/her field of specialization in the
> database once an editor successfully logs into the web
> site. Therefore, it takes an "action" (Action TWO)
> that tells the business tier to find the "keyValue" in
> the database. And should I put the "keyValue" in a
> session object.
One method that I use is to create a user bean and store that in the
session at login. This bean could include your editor's field of
specialization, so that you don't need an extra action.
Secondly, you could drop the Action One by incorporating the field of
specialization as a part of one SQL statement, so that you never
actually extract the field of specialization from the DB. I.e. something
like this:
SELECT article_title, article_text FROM app_user, article
WHERE app_user.user_name = ?
AND app_user.field_of_specialization = article.field_of_specialization
Alternatively if you still want to do 2 actions, I have seen people
handle it in various ways: (1) get the action-forward in your action and
modify the path to add a query_string with your keyValue on it (2) put
the keyValue in a cookie (3) as you said, put it in the session. 2 & 3
have the disadvantage that they could be overwritten if the user has
more than one browser window open.
HTH
Adam
--
struts 1.1 + tomcat 5.0.12 + java 1.4.2
Linux 2.4.20 RH9
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