title: Form_for with url, format and html options
body: <p>I feel like im missing something simple here. I am using the form_for helper with an object. I specify the url, the format, and html method. However, when rendered the url in the action attribute does not pick up the format. Here's my code:</p>
  
  <pre><code>=form_for(@site, url: compile_documents_path(@site), format: :csv, html: { method: :post}) do |f|
  </code></pre>
  
  <p>My controller is setup to respond to a csv format, and i simply call a to_csv method on the site object.</p>
  
  <p>Any ideas as to why it's not working as expected.</p>