Rails send_data streaming PDF as bytes, unless route accessed directly - ruby-on-rails

Question

I've got a simple Rails app that downloads a PDF from a (private) S3 bucket and serves it to the browser.
# app/controllers/file_controller.rb
class FileController < ApplicationController
def send_pdf
s3_file = Aws::S3::Resource.new(
region: "us-east-1",
access_key_id: S3_ACCESS_KEY_ID,
secret_access_key: S3_SECRET_ACCESS_KEY
).bucket('bucket-name').objects({prefix: "file_name"}).first.get.body.string
send_data s3_file, filename: "FileName.pdf", type: 'application/pdf', disposition: 'inline'
end
end
# config/routes.rb
Rails.application.routes.draw do
get 'file', to: 'file#send_pdf', defaults: { format: 'pdf' }
end
When accessing the route directly via URL, it displays the PDF fine.
When opening a link to the route in a new tab, it displays the PDF fine.
When opening a link in the same tab, the PDF data streams as text to the browser instead.
The same behavior occurs in Rails 4 and 5.
I'm probably missing something annoyingly minor here, but how can I get the open in the same tab behavior to properly display the PDF instead of streaming bytes as text?
Update 1:
Chrome gives a Failed to load PDF document error when send_pdf is modified to use send_file instead of send_data. (This error happens regardless of link click or direct route request.)
def send_pdf
# S3 download
temp_file = "#{Rails.root}/tmp/file.pdf"
File.open(temp_file,"wb") do |f|
f.write(s3_file)
f.close
end
send_file temp_file, filename: "FileName.pdf", type: 'application/pdf', disposition: 'inline'
File.delete(temp_file)
end

Answer 1

Have you tried send_file instead of send_data?
http://apidock.com/rails/v4.2.1/ActionController/DataStreaming/send_file