Rails - May 2008 - file_field throws exception when field is left blank

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
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On 5/12/08, dino d. <dinodorroco-/E1597aS9LQAvxtiuMwx3w@public.gmane.org>
wrote:
>  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?
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


-- 
Greg Donald
http://destiney.com/

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