File upload validation

[eluser]pistolPete[/eluser]
[quote author="stef25" date="1239492798"] it seems 'userfile' is the way to go as first param for the set_rules function. ...
again id like to stress that pistolpete's solution in post#2 (what i was basing myself on all afternoon!) does NOT work.[/quote]

This was almost a verbatim copy from one of my projects and it's working fine there.

Do you use something like this?

Code:

$this->form_validation->set_rules('userfile', 'whatever', 'callback__do_upload');

I doubt whether that is working because a file upload is saved in the $_FILES array but the input fields which are processed by the form validation class are in the $_POST array.

Could you please provide the full controller and view code?

[quote author="stef25" date="1239543705"]do you have to declare $image_data as private, public, ... ? if so, where?[/quote]

Have a look at this post: forums/viewreply/551725/
I'd use private as this is only controller internal data.
Don't return $image_data in your callback function, save it in a class variable.

One reason is this: user_guide/libraries/form_validation.html#callbacks

You can also process the form data that is passed to your callback and return it. If your callback returns anything other than a boolean TRUE/FALSE it is assumed that the data is your newly processed form data.