Java SE (Java Platform, Standard Edition)

One of the big things still missing from the JFX space (especially where JEE is concerned) is forms and form validations. Maybe you guys have been luckier but at least 80% of the screens I've had to build in my career have been boring old forms - enter data in the fields, validate them and hit submit.

So, I've been hacking around on this to try and get a pattern and hopefully some reusable classes for doing this in JavaFX. I have something that works but the code is verbose and less than elegant. I'm hoping some of you guys might want to kick around some ideas on this with me here. If we can come up with something that works, I'd like to either include it in [url http://www.zenjava.com/jfx-flow/]JFX Flow, or put it out as a separate open source project (whichever makes more sense).

What I think needs to be supported:

* Map between a normal Java bean and the fields on a form
* Validate the data, i.e. specifying the constraints on a field and then checking those constraints
* Show a validation summary at the top of the form
* Highlight individual fields if they have validation errors
* Support auto-validation, i.e. the validation highlights and messages will instantly update as the user types

Some extra restrictions:

* The data input will ideally be a normal bean and so it won't have observable values on it. In most projects I use, the beans are coming from the server and sometimes may be shared between desktop client and a jsp/web client, or even be a third party API so they can't be changed. End result: we don't want any JFX complexities or dependencies in our server code (design leak). This rule could be bent but only as a last resort.

* The validations must be defined relative to the normal data bean not a JFX model or controller, etc. This is so the bean can be validated on the server as well as the client. The server must do validation to prevent dodgy data getting in (never trust a client). Ideally we don't want to be specifying the validations in two places (i.e. once for the client and once for the server) as this creates maintenance problems and weakens the integrity of the system over time.

* Ideally the validation mechanism will be based on [url http://java.dzone.com/articles/bean-validation-and-jsr-303]JSR 303 - Bean Validations as this is quite nice. This is flexible however if there is a suitable alternative that integrates better.

To give us something to reference in conversation, I've created a small working sample. This is only meant to be a rough starting point (at best) and I'd really like to get feedback on both the code (i.e. should we have a 'presentation model', how could bindings be better used, etc) and the general way I'm representing errors (i.e. should we use tooltips to show errors, or actually show the errors next to the field, should we use border colours or put a little exclamation mark over the field, should the fields be auto-validated or only validated on submit, etc).

The example is a single form for editing a person. It has three fields, first name, last name and gender. When the form is blank, auto-editing is off. When the user submits the form it is validated and from that point on auto-validating is on. Error fields are highlighted with a style change, and a tooltip is added with details (I think we can do better - what's your ideas?).

I have used all plain Java to keep thngs simple, but I'd be looking for the end result to translate to FXML as well. I've also coded everything into the one class but the eventual goal would be to have the common stuff moved out to reusable base classes, etc.

Here's a workspace with some example code in it: http://code.google.com/p/jfxee/source/browse/trunk/jfxforms/
Here's a running deploy of that code: http://zenjava.com/demo/form/forms.html

(edit: I've moved the code to its own project and changed the url for the launch - the values above are the new, correct ones)

Looking forward to hearing some thoughts on this topic.

Edited by: zonski on 01-Dec-2011 13:41