I copy properties using BeanUtils where possible, and for cases where that doesn't work (there are many) I do it manually in the Action.
The cases where BeanUtils.copyProperties() doesn't work are when the business object has nested properties, or where the type of the property is not one of the native types. If anybody has a nice solution to these I'd like to hear it... I've been thinking about extending BeanUtils to understand my ObjectID class, java.util.Date, etc.
On Friday, May 30, 2003, at 02:04 PM, Jordan Reed wrote:
I've been playing #3 (Just included the value objects in the form) and run
into one of those things that probably makes people break into tears.
I have int types in the value object... And since they cannot be null, when
the form is prepopulated or repopulated they appear as "0" instead of being
blank or what the user entered. Sad.
-jdr
On 5/28/03 9:53 PM, "Andrew Hill" <[EMAIL PROTECTED]> wrote:
2 & 3 generally end in tears. They sound nice, but when you get down to the
fiddly bits you will find it more problematic than you expect.
As you mention, the action form is very much a view object. For a start
everything in the actionForm will be strings, while your business object
probably will not be. Secondly, while there is considerable overlap between
your value object and your form, you will find (especially as your ui gets
more complex) that the correlation is not 1 to 1 and that you are exerting a
lot of effort to try and keep the two the same.
Approach 3 is probably the worst - unless its for read only display - in
that if the user enters a value that doesnt convert to your value objects
property type you will want to redisplay the offending value string the same
as the user typed it for them to correct it.
Your best bet is to use approach 1. You may be interested to note that the
BeanUtils class does have some methods that can make life simpler for you -
copying property values and doing type conversions automatically (if I
recall correctly).
(Actually I generally copy the properties the 'hard' way, one by one in my
action)
-----Original Message----- From: Jordan Reed [mailto:[EMAIL PROTECTED] Sent: Thursday, 29 May 2003 12:29 To: Struts Users Mailing List Subject: Populating Value Objects for the Business Tier
All,
I'm on a team that's trying to decided on a best practice for passing on
populating our value objects that get passed to our business layer. We
currently have three techniques we've though up and I'm wonderful if anyone
has a strong opinion on which one may be the "best" and why.
The basic problem is that the user enters information into a form. The form
is a presentation object, and should not be passed to the business layer.
So it's information needs to be in a presentation-agnostic interface before
being passed to the data layer.
1) Have the action class copy information from the form to a value object.
Have a view helper copy information from the value object into the form (for
pre-population)
2) Have the form implement a value-object-like interface. The business
layer accepts objects with these business interfaces. This way it is
possible to pass the form objects to the business layer without the business
layer knowing that they are presentation objects.
3) Have the form simply include value objects as properties. Then use the
nested taglibs to populate the value objects. This way the Action can just
pull the value object off directly and pass to the business layer. A view
helper can just set the value object on the form.
-jdr
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