Givler, Eric wrote:
I don't know why, but I've been wondering how to handle the issue of presenting
formatted data to a user in a struts-based application.
That is, is it:
1. Backend bean is strongly typed and data is read into this via Service method
of some sort
2. Action takes backend data and through a helper object formats it and places into ActionForm properties as formatted values
3. User enters data
4. Validation ensures formatting is ok (Struts Validator or other)
5. If ok, helper object parses results and creates business bean (DTO) to
persist to back end
6. Invoke service method to store it
That sounds pretty reasonable, yes.
I've looked at FormDef, but the App I've inherited to fix contains a lot of front-end
code (in JSP) that adds up values and presents them. Now that the form bean (a map)
contains all Strings, I have to then run <fmt:parse> against all of this data
to add it up. I guess I could add it up in the Action when I first read the database
values and created some other request attributes, and made sure these attributes were
refreshed if I hit save. If validation occurs and errors are thrown, where do I get
those database values again to add easily? I can't add the unparse-able numbers (or
I add them as zero) Do I throw the DTO into the form bean as a property?
It sounds like your JSPs have a lot of data processing logic in them.
Ideally, all the data derivation (summing rows, etc.) should happen in
your application logic -- in an action, or a service the action calls.
The form bean or other objects you pass to the JSP should have all the
data needed to display the page, already calculated.
When the form is submitted, you validate all fields and, if any fail,
redisplay the form in the state it was when it was submitted. It's up to
you and your requirements whether calculated data should be updated in
this case, or whether you should (for example) display 'n/a' for fields
that depend on invalid inputs.
I'm not sure I like the idea that the Business bean returns the formatted data,
which I've seen in Struts In Action. Not that I have anything against the
book, but if the formatting is based on a Locale, and a locale is user-based,
then it seems like the formatting should be occurring in the front-end like in
JSF, rather than the other way around.
There's a difference between formatting and data aquisition /
processing. Once you clean up the way data gets to the page, issues
about how and where to format it for display should be easier to address.
Also, is there something that works for multi-record entry with formatting as
well? I didn't understand how form-def was supposed to handle this, and the
same issue would apply with summing the result records (actually sum, min, and
max)
I'm not sure how this relates. Perhaps the question is a bit too general.
I'm all ears for suggestions, and thanks.
L.
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