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From "Malcolm Edgar" <>
Subject Re: DataView status
Date Mon, 16 Oct 2006 01:57:36 GMT
Hi All,

I have been spending some time getting familiar with the DataView /
DVmodeller code base from the Cayenne 1.2.1 build.  This code is
definitely a work in progress, compared with the rest of the Cayenne
code base but I think there is a lot of great work in there.

Things I have been doing is:

* Making DVModeller more productive, auto populating fields, saving prefs, etc.

* Removed the jdom dependency for the DataView package, to enable the
DataView core to run on WebSphere without patching jdom.

* Added ThreadLocal access pattern, as is done with DataContext, to
support server side usage.

* refactored out dependent code Swing into a dataview.swing package

* Unit tests and Javadoc

I think the DataView concept is very useful, and has benefits over an
Java 1.5 annotation based meta data approach.  When building
applications you often have the use case where on form where some
fields are not required (or visible), but latter on in the process
they become mandatory (in the database these fields are not

With DV you can have different views across the same object entities
to support these different requirements.  With a straight annotation
based approach I can't see how it would support these scenarios.

>From a conceptual point of view I think associating UI and validation
meta data for objects and their fields, is a better approach than 1.5
annotations. I think annotations are used in JSF for this purpose.

Extra fields which could be added the the ObjFieldView include:
* sortable - UI hint for columns
* tooltip - for field help
* width - UI field / column width hint

Validation meta data will be more complex, and possibly should be
represented in another class. Information I would like to see would
* required
* max length
* min length
* min value (for numeric values)
* max value  (for numeric values)

The existing edit format combined with the JavaClass can be used for
additional validation.

I haven't figured out how a list of values (for a select / ComboBox)
is represented in the DV design.

Anyway just some random thoughts.

regards Malcolm Edgar

On 10/11/06, Andrus Adamchik <> wrote:
> On Oct 10, 2006, at 5:22 PM, Adrian Wiesmann wrote:
> > Unfortunately the SOBF tool has no full time developer and does not
> > bring
> > in any money and therefore I can make no commitment. But I am
> > willing to
> > supply the "cayenne core team" with patches and diffs. Although
> > this would
> > require somebody from the core team willing and interested to go
> > through
> > my/our stuff and work that into the official source.
> That'll work, but will depend on the quality of patches submitted via
> Jira. As long the patches are well-organized, split into manageable
> chunks and documented via Jira comments, I personally have no problem
> committing them.
> > And of course I would welcome if I would not be the only one
> > volunteering :)
> Quite possibly this won't be the case.
> >> I like your website :-)
> >
> > How come?
> This wasn't an ironic comment. For an open source project the design
> is clean and professional.
> Andrus

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