title: How to check in rails uploaded file type?
body: <p>How can i see what type of file is comming?
  For example, csv or xls...
  Give code please...
  I get file so:</p>
  
  <pre><code>aut_name = uploaded_io.original_filename
        File.open(Rails.root.join('public', 'uploads_prices', uploaded_io.original_filename), 'wb') do |file|
          file.write(uploaded_io.read)
        end
        as_load(aut_name)
  </code></pre>
  
  <p>Maybe by MIMO, but how?</p>