rails 4 aws-sdk v2 file path error and/or implicit conversion error

I am following this tutorial which looks like its written for Rails 4 with aws-sdk version 1, I am using version 2, my controller is

class UploadsController < ApplicationController
  def new
  end

  def create

    bucket_name = 'my-first-bucket-tutorial986'

   # file_name = params[:file][:tempfile].original_filename

   # file_name = file_params.original_filename

    file_name = File.basename( params[:file], File.extname(params[:file]) ).to_s

    s3 = Aws::S3::Resource.new(options = {region: 'Ireland'})

    s3.bucket(bucket_name).object('target').upload_file(file_name)

   # obj = S3_BUCKET.objects[file_params.original_filename]
    #obj = Aws::S3::Object.new(params[:file].original_filename, options = {bucket: 'my-first-bucket-tutorial986'})
    # Upload the file

   # obj.upload_file(params[:file], options = {acl: :public_read})
=begin    obj.write(
      file: params[:file],
     # file: file_params,
      acl: :public_read
    )
=end
    # Create an object for the upload
    @upload = Upload.new(
            url: obj.public_url,
        name: obj.key
        )

    # Save the upload
    if @upload.save
      redirect_to uploads_path, success: 'File successfully uploaded'
    else
      flash.now[:notice] = 'There was an error'
      render :new
    end
  end

  def index

    @uploads = Uploads.all

  end

  private

  def file_params

    params.require(:file) #.permit(:name, :age)

  end

end

The error I am getting now is "no implicit conversion of ActionDispatch::Http::UploadedFile into String" but previously the path to the file could not be found when using the params[:file] or the file_params.original_filename

the view is

<h1>Upload a file</h1>

<%= form_tag uploads_path, enctype: 'multipart/form-data' do %>
    <%= file_field_tag :file  %>
    <%= submit_tag 'Upload file' %>
<% end %>