file_field throws exception when field is left blank

rubyonrails-talk
1

hi -

I'm adapting a file upload from the Agile book. I have two models, Challenge and MediaFile. The form looks like this:

<%form_for :challenge, :url => {:action =>:create}, :html=>{:multipart=>true} do |f|%> <%fields_for :media_file do |m|%>       Please select a media file: <%=m.file_field :uploaded_data%> ...

The MediaFile model has a method defined 'uploaded_data'

def uploaded_data=(picture_field)     name = base_part_of(picture_field.original_filename)     content_type = picture_field.content_type.chomp     data = picture_field.read end

This works fine, unless the user doesn't select a file for upload. In this case, picture_field is a blank string, and the model has no attribute original_filename, etc. So the exception is:

undefined local variable or method `original_filename' for #<MediaFile: 0x574b3c8>

The question is, how do I detect when a user hasn't selected a file for upload, and gracefully add an error to the errors collection? I wonder if this has something to do with having two models? Like I said, it works just fine when the user selects a file.

Thanks for any help, Dino

2

Rescue the exception and add an error to the model.

begin   # put whatever explodes here rescue   @foo.errors.add( :file, 'oops' ) end

http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_exceptions.html

http://api.rubyonrails.com/classes/ActiveResource/Errors.html#M000801