Ruby Rails: Upload File - ruby-on-rails

Question

I am trying to follow this tutorial. It has written in previous version of Rails and I am using Rails 4. I am trying to upload file but I am getting following error:
NoMethodError in UploadController#uploadfile
undefined method `[]' for nil:NilClass
Extracted source (around line #3):
class DataFile < ActiveRecord::Base
def self.save(upload)
name = upload['datafile'].original_filename
directory = "public/data"
# create the file path
path = File.join(directory, name)
Rails.root: C:/Ruby193/mylibrary
Application Trace | Framework Trace | Full Trace
app/models/data_file.rb:3:in `save'
app/controllers/upload_controller.rb:6:in `uploadfile'
Here is data_file.rb
class DataFile < ActiveRecord::Base
def self.save(upload)
name = upload['datafile'].original_filename
directory = "public/data"
# create the file path
path = File.join(directory, name)
# write the file
File.open(path, "wb") { |f| f.write(upload['datafile'].read) }
end
end
Here is controller upload_controller.rb
class UploadController < ApplicationController
def index
render :file => 'app\views\upload\uploadfile.html'
end
def uploadfile
post = DataFile.save(params[:upload])
render :text => "File has been uploaded successfully"
end
end
Here is uploadfile.html
<h1>File Upload</h1>
<%= form_tag({:action => 'uploadfile'}, :multipart => true) do %>
<p><label for="upload_file">Select File</label>
<%= file_field 'upload', 'datafile' %></p>
<%= submit_tag "Upload" %>
<% end %>
What should I do? Thanks in advance

Answer 1

It looks like params[:upload] isn't what you think it is. You forgot to set the form to be multipart. If fixing that doesn't make it work, start inspecting params to see what you're actually getting.
def uploadfile
puts params.inspect # Add this line to see what's going on
post = DataFile.save(params[:upload])
render :text => "File has been uploaded successfully"
end
Also, it's not a great "answer," but I've had good success using paperclip to handle file uploads. If you just want something that works (rather than learning how to do it yourself), check into that.