Unable to pass uploaded file to model - ruby-on-rails

Question

I am relatively new to rails cannot get the following code to work. I am trying to upload a data file (Excel or csv), copy it to a temp folder and create a record in a Datafiles model which holds basic file information, such as filename, type, and date. Then I want to read the file and use the data to create or update records in several other models. If all goes well, move the file to a permanent location and write the new path in the Datafiles record.
Controller:
def new
#datafile = Datafile.new
respond_to do |format|
format.html # new.html.erb
format.xml { render :xml => #datafile }
end
end
def create
#datafile = Datafile.new(params[:upload])
#datafile.save!
redirect_to datafile_path(#datafile), :notice => "Successfully imported datafile"
rescue => e
logger.error( 'Upload failed. ' + e.to_s )
flash[:error] = 'Upload failed. Please try again.'
render :action => 'new'
end
View:
<%= form_for #datafile, :html => {:multipart => true} do |f| %>
<p>
<%= f.label(:upload, "Select File:") %>
<%= f.file_field :upload %>
</p>
<p> <%= f.submit "Import" %> </p>
<% end %>
Model:
require 'spreadsheet'
class Datafile < ActiveRecord::Base
attr_accessor :upload
attr_accessible :upload
before_create :upload_file
def upload_file
begin
File.open(Rails.root.join('uploads/temp', upload.original_filename), 'wb') do |file|
file.write(upload.read)
self.filename = upload.original_filename
Spreadsheet.client_encoding = 'UTF-8'
#book = Spreadsheet.open(file.path)
self.import
end
rescue => e
#upload_path = Rails.root.join('uploads/temp', upload.original_filename)
File.delete(#upload_path) if File::exists?(#upload_path)
raise e
end
end
def import
case #book.worksheet(0).row(0)[0]
when "WIP Report - Inception to Date"
self.report_type = 'WIP'
puts 'report_type assigned'
self.import_wip
else
self.report_type = 'Unknown'
end
end
def import_wip
self.end_date = #book.worksheet(0).row(0)[3]
puts 'end_date assigned'
end
def formatted_end_date
end_date.strftime("%d %b, %Y")
end
end
However, it fails and the rails server window says
Started POST "/datafiles" for 127.0.0.1 at 2011-05-24 16:05:25 +0200
Processing by DatafilesController#create as HTML
Parameters: {"utf8"=>"✓", "datafile"=>{"upload"=>#<ActionDispatch::Http::UploadedFile:0xa0282d0 #original_filename="wip.xls", #content_type="application/vnd.ms-excel", #headers="Content-Disposition: form-data; name=\"datafile[upload]\"; filename=\"wip.xls\"\r\nContent-Type: application/vnd.ms-excel\r\n", #tempfile=#<File:/tmp/RackMultipart20110524-14236-1kcu3hm>>}, "commit"=>"Import"}
Upload failed. undefined method `original_filename' for nil:NilClass
Rendered datafiles/new.html.erb within layouts/application (54.5ms)
Completed 200 OK in 131ms (Views: 56.3ms | ActiveRecord: 0.0ms)
I have rspec model tests that pass and controller tests that fail to redirect after saving. I can post them if it would be useful.
I inserted the raise #datafile.to_yaml and got the following in the terminal.
ERROR RuntimeError: --- !ruby/object:Datafile
attributes:
filename:
report_type:
import_successful:
project:
begin_date:
end_date:
created_at:
updated_at:
attributes_cache: {}
changed_attributes: {}
destroyed: false
marked_for_destruction: false
persisted: false
previously_changed: {}
readonly: false
I notice that :upload is not listed. Can I set model instance variables from the form? :upload is an instance variable, not an attribute, because I do not want to keep the uploaded file in the database (just its path to the local directory). If I cannot set instance variables in the view's form, any suggestions? Does it make sense (in terms of MVC) to upload the file to a temp folder in the controller, then create a model record by passing it the temp file's path?

Answer 1

Hello I am pretty new to Rails and was strugling with this as well I found a solution though it probably isn't the best. It does work though.
in you model make a public function called import_upload
def import_upload( upload )
#uploaded_file = upload
end
now in your controller you can explicitly pass it. I don't know why this doesn't happen automatically if you make an attr_accsessor with the same name as the file_field but this was the solution that worked for me.
def new
foo = Foo.new( params[:foo] )
foo.import_upload( params[:foo][:uploaded_file] ) #This is were the majic happens
#Do your saving stuff and call it a day
end