hook_validate called twice

Yes, the validate functions are called by drupal_get_form et all, like they should be. The second time, they're called by node_form_add_preview.

I don't know whether this is a big problem for anyone, I just wanted to mention it and see how it is caused.

The preview stuff happens before the drupal_validate_form call and is needed. The drupal_validate_form call is just not smart enough to know that it has been called on the same form but that can be fixed...

Good solution, but, wat does the #validated flag in _form_validate (http://drupaldocs.org/api/head/function/_form_validate) do exactly?

that's form API level checker but if you look at the code flow it's a copy of the form that's changed.

+1, code looks good. this should work ok w/ multipage forms, as the current implementation only needs to be validated once.

The form gets recursed by _form_validate, passing a copy of subelement to that function. What then is the use of #validated? In what situation would !$elements['#validated'] at the top of _form_validate ever result in false?

tested the patch using the multipart example module. all validate functionality seems to work fine.

naquah: #validated can be marked for any form element prior to the validation code running. probably not a common use case, but still possible...

applied

naquah, the whole form API is loaded with safety belts. #processed, #after_build_done, #theme_used, #printed just a few comes to my mind. If you are recursing AND such belts add little code, it's better for them to be there. I can rwite you a form array which would recurse on itself using some reference magic. But are you sure you want to have nightmares of that :) ?

Robert, ask nedjo, currently he knows best. Or read the code, that's what I'd do if I'd want to answer :)

chx, thanks for clearifying it... and I have enough nightmares from other things already. Thanks again, this is a good way to learn stuff.