JavaFX Form Validation
jonathan.giles at oracle.com
Mon Jun 11 02:01:13 PDT 2012
My understanding of JSR-303 is that it is well past the stages of being
active. According to , it starting in July 2006, and produced its
final release (along with final API) in November of 2009.
Also, from my understanding of JSR-303, it appears to be more focused on
the Java EE needs of a container such as Hibernate (one component of
which is the reference implementation of JSR-303). I would imagine that
this would lead to it being far more complex than is necessary in a
However, I am not ruling it out, but I just worry that it may be
ill-fitting for JavaFX. I would be totally happy to be proven wrong, and
will look into it more tomorrow to be sure.
On 11/06/2012 8:47 p.m., Florian Brunner wrote:
> I haven't worked with JSR-303, yet, but I would appreciate if the Java community could come up with a validation framework which can be used consistently on various layers.
> If JSR-303 currently doesn't fit the needs of JavaFX, maybe the JavaFX team could get involved in JSR-303 to make sure it fits the needs of JavaFX as well?
> Am Montag 11 Juni 2012, 01:52:10 schrieb Jonathan Giles:
>> Hi all,
>> I'm currently in the very, very early stages of developing a validation
>> API for future inclusion into JavaFX. I thought rather than get too far
>> into the research and development of a proof of concept, I would see
>> what you all think. Any feedback now would be very useful.
>> Essentially, there are a few common styles related to form validation.
>> Some of the more likely approaches include:
>> * The 'JGoodies Validation framework'  approach, where the
>> developer provides a Validator that will then run over the form and
>> gather feedback to return to the user (for example, it would test
>> that the 'name field' is not empty, and that the email address is of
>> the correct style - if either of these rules are invalid, the
>> Validator would return ValidationMessage instances inside a
>> ValidationResult). If validation fails the user is shown the text
>> out of the ValidationMessage feedback, otherwise the form would
>> submit as per usual. This validation may happen at a number of times
>> (during form submission, when focus is lost, as a key is typed,
>> etc). The nice thing about this approach is that the Validator can
>> be a part of the domain model, the presentation model, or a separate
>> thing altogether.
>> * The JSR-303 approach which uses annotations to indicate the rules
>> applicable to each field. These annotations are on the domain model,
>> and therefore assumes that the form is directly tied to a domain
>> object (which may not always be correct). I think the JSR-303 API is
>> too complex for what is needed in JavaFX, but a similar
>> implementation could be developed with a simpler API that follows
>> this approach.
>> * For lack of a better reference point, the FXForm approach  which
>> encapsulates the validation inside a Form object that can be placed
>> in the scene. I know this isn't explicitly (in the case of FXForm)
>> about validation, but I think it is another approach to consider.
>> So, what does JavaFX need out of a validation framework? It's really
>> five things (I think):
>> 1. A way for developers to validate a form by providing some means of
>> specifying rules, as well as a way to specify when it runs, how it
>> is visually represented, etc.
>> 2. A way for the validation to impact upon the visual state of the form
>> (using consistent CSS pseudoclass states / style classes, as well as
>> by showing custom overlays, error messages beside the component (or
>> grouped together at the top of the form)). There must be API to
>> specify all of this.
>> 3. Convenient API to simplify the validation process  (e.g.
>> isEmpty(String), isAlphanumeric(String), etc, etc, etc).
>> 4. An API that does not require it be integrated with UI controls.
>> Doing so would prevent 3rd party UI controls to be able to be
>> validated without also implementing the API, which may prove
>> burdensome. Instead, the validation API should be separate.
>> 5. A means to integrate nicely with the bindings and properties API
>> present in JavaFX today.
>> Of the three approaches above, my personal preference is to follow the
>> JGoodies approach as I think it is the most powerful and flexible.
>> However, nothing is set in stone and I want to learn what others think.
>> Note that at present this research does not extend to considering
>> whether there should be API related to automatically generating a form
>> from a (JavaFX) bean (and making use of the validation API to ensure the
>> input is correct). However, I am not against discussing this topic as
>> well, as long as it too integrates nicely with the rules above, as well
>> as the validation API itself, obviously. This research may full into
>> requirement three above.
>>  http://www.jgoodies.com/freeware/libraries/validation/
>>  https://github.com/dooApp/FXForm2
>> -- Jonathan
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