"render :nothing => true" returns empty plaintext file?

UPDATE: This is an old answer for legacy Rails versions. For Rails 4+, see William Denniss' post below.

Sounds to me like the content type of the response isn't correct, or isn't correctly interpreted in your browser. Double check your http headers to see what content type the response is.

If it's anything other than text/html, you can try to manually set the content type like this:

render :nothing => true, :status => 200, :content_type => 'text/html'

Since Rails 4, head is now preferred over render :nothing.¹

head :ok, content_type: "text/html"

# or (equivalent)

head 200, content_type: "text/html"

is preferred over

render nothing: true, status: :ok, content_type: "text/html"

# or (equivalent)

render nothing: true, status: 200, content_type: "text/html"

They are technically the same. If you look at the response for either using cURL, you will see:

HTTP/1.1 200 OK
Connection: close
Date: Wed, 1 Oct 2014 05:25:00 GMT
Transfer-Encoding: chunked
Content-Type: text/html; charset=utf-8
X-Runtime: 0.014297
Set-Cookie: _blog_session=...snip...; path=/; HttpOnly
Cache-Control: no-cache

However, calling head provides a more obvious alternative to calling render :nothing because it's now explicit that you're only generating HTTP headers.

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1. http://guides.rubyonrails.org/layouts_and_rendering.html#using-head-to-build-header-only-responses