Multipart form with empty file_field submits nil

So, just to clarify, is this something that needs to be changed in Rack, or in the behavior of plugins like Paperclip?

it was not fixed in 2.3RC2

Yeah, still doing:

params[:hinge].delete(:image) unless params[:hinge][:image]

before

@hinge.update_attributes(params[:hinge])

Should it be fixed in paperclip?

Follow to: http://thoughtbot.lighthouseapp....

I don't think "" is a correct value, but setting it to nil is problematic as file fields can't, unlike any other fields, hold a prepopulated value. So while other fields can simply set themselves to themselves, file fields set to nil will overwrite. While I think nil is technically correct in the case of HTML form submission, it's not in the case of acting like an attribute.

Perhaps the best case is for the Rack multipart handler to simply leave the file out of the params if there is no upload, similarly to how unchecked checkboxes are left out.

fwiw I'd agree that excluding file fields with no upload from params makes more sense than leaving them in and set to nil.

Please submit a patch to rack core ASAP!

I'm attaching a patch that sets blank uploads to "" instead of nil. It appears to fix the problems with Paperclip in my testing.

I can't figure out how to ignore the attribute altogether. Maybe somebody else can give it a shot...?

Cross-posted here:

http://groups.google.com/group/r...

I've submitted a slightly different patch over on the rack lighthouse that removes the empty file param instead of setting it to nil/blank.

I'll post a note on the rack mailing list too...

Rob, your patch works for me. Thank you!