Hey Wichert,

really? At least that's what I understood when you said:

""" If you asked someone:

During preprocessing of a submitted request you stored some data in the database. What do you expect to happen if the form validation fails?

1. the stored data disappears

2. the stored data is saved

Everyone would pick 1. """

Wichert, it can't! Or if it can, I can't see where... :-/

Follow the path with me:

- You press the 'Save' button in the Archetypes form edit screen

- That form edit screen is a ControllerPageTemplate (base_edit.cpt) with validate_base.vpy as the unique validator

- validate_base.vpy calls BaseObject.validate() to check for errors

- BaseObject.validate() calls BasicSchema.validate() which in turn calls widget.process_form() for all fields

- We have a ReferenceField which uses a special reference widget, UploadReferenceWidget, which was designed to be a simple replacement for the default ReferenceWidget

- That widget receives a FileUpload object via REQUEST, proceeds with a 'File' creation and only returns its UID as the widget value

- Now that there's already a File in ZODB, the validation of another field fails, let's say 'title' was required but nothing was passed

- At this point the validation failed and you're back to the edit form screen with no chance to abort the transaction

Do you see the problem?

The point is: the only place where you can do additional stuff without changing any default Archetypes/CMFFormController settings is in the widget process_form() call, while at validation phase.

I'm still strongly arguing that CMFFormController would be the best place to have this fixed, but I can live with a change on Archetypes.

If you're worried about the 'transaction.abort()' being called by validate_base.vpy, I can suggest to fire a IObjectFailedValidation (or something like that) event there, that can be subscribed by third party code (the special widget, in this case).

--

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Dorneles Treméa · Developer, Jarn · www.jarn.com

Plone Solutions, Development, Hosting and Support

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