I'll try to be brief as possible here. I put up a war file at
http://www.reumann.net/reumann/struts/actionProblem.html that you can
download and place in your webapps directory and see an example of how
there are problems to consider when you forward from one Action to another
(Action chaining this is called- lot about it on the Struts list).
The idea that you can build navigation without concern about your underlying
FormBeans only 'definitely' holds true when you are not forwarding to another
Action. When you forward to another Action there are things to consider. I
started the "My Headache" thread because of a situation that came when
forwarding from one Action to another Action and I mentioned that if you
could avoid this you are better off.
If you run the action_problem app at the link above you'll see just one
very small example- not the exact example I ran into but something
similar. If you don't feel like looking at the war here is a brief summary
of the situation:
Two form beans:
BookBean
private String title;
private String description;
private String bookNote;
ChapterBean
private String title;
private String description;
private String content;
Two Dispatch Actions
BookAction
ChapterAction
1) On bookForm.jsp to fill out title, description, bookNote and submit
will save. Form submits to BookAction
2) BookAction has dispatch "save" and does the save, but now you want the
user to fill out the ChapterBean and save that you so you have the
BookAction foward to the ChapterAction with dispatch "edit"
3) Now you are on the editChapter.jsp but NOTICE the title and description
properties - they are filled in with the Book title and Book description!
This makes sense though since the Request object is propogated along from
one Action to the next when your forward to another Action (and
ChapterBean has a title and description property as well).
So the point I'm just trying to make is there are things to watch out for
when Action chaining. Most agree that Action chaining serves it's purpose
when you have one large FormBean that you need populated over several
pages (ie- imagine online Tax Form preperations). However, in most
circumstances it seems best to avoid forwarding one Action to another
Action.
My "headache' example was much more complex than the above example but it
basically was a result of forwarding from one Action to another Action. (
I had a nice nested beans detail display page and a link to "add a Task"
from that page. When you clicked on the link to "add Task" you go through
"taskAction" and when finished after Save you'd forward to the
"detailAction" to bring you back to the detail page. Well when that
occured Request properties that were on the taskForm.jsp were setting
properties of other beans on the detail page since they had similar
names).
--
Rick
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