send_file

Sends the file. This uses a server-appropriate method (such as X-Sendfile) via the +Rack::Sendfile+ middleware. The header to use is set via config.action_dispatch.x_sendfile_header. Your server can also configure this for you by setting the X-Sendfile-Type header.

Be careful to sanitize the path parameter if it is coming from a web page. send_file(params[:path]) allows a malicious user to download any file on your server.

Options:

• :filename - suggests a filename for the browser to use. Defaults to File.basename(path).

• :type - specifies an HTTP content type. You can specify either a string or a symbol for a registered type with Mime::Type.register, for example :json. If omitted, the type will be inferred from the file extension specified in :filename. If no content type is registered for the extension, the default type application/octet-stream will be used.

• :disposition - specifies whether the file will be shown inline or downloaded. Valid values are "inline" and "attachment" (default).

• :status - specifies the status code to send with the response. Defaults to 200.

• :url_based_filename - set to true if you want the browser to guess the filename from the URL, which is necessary for i18n filenames on certain browsers (setting :filename overrides this option).

The default Content-Type and Content-Disposition headers are set to download arbitrary binary files in as many browsers as possible. IE versions 4, 5, 5.5, and 6 are all known to have a variety of quirks (especially when downloading over SSL).

Simple download:

send_file '/path/to.zip'

Show a JPEG in the browser:

send_file '/path/to.jpeg', type: 'image/jpeg', disposition: 'inline'

Show a 404 page in the browser:

send_file '/path/to/404.html', type: 'text/html; charset=utf-8', disposition: 'inline', status: 404

You can use other Content-* HTTP headers to provide additional information to the client. See MDN for a list of HTTP headers.

Also be aware that the document may be cached by proxies and browsers. The Pragma and Cache-Control headers declare how the file may be cached by intermediaries. They default to require clients to validate with the server before releasing cached responses. See www.mnot.net/cache_docs/ for an overview of web caching and RFC 9111 for the Cache-Control header spec.