Action Controller Data Streaming

Methods for sending arbitrary data and for streaming files to the browser, instead of rendering.

Methods

Included Modules

Instance Private methods

send_data(data, options = {})

Sends the given binary data to the browser. This method is similar to render plain: data, but also allows you to specify whether the browser should display the response as a file attachment (i.e. in a download dialog) or as inline data. You may also set the content type, the file name, and other things.

Options:

  • :filename - suggests a filename for the browser to use.

  • :type - specifies an HTTP content type. Defaults to application/octet-stream. You can specify either a string or a symbol for a registered type with Mime::Type.register, for example :json. If omitted, 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.

Generic data download:

send_data buffer

Download a dynamically-generated tarball:

send_data generate_tgz('dir'), filename: 'dir.tgz'

Display an image Active Record in the browser:

send_data image.data, type: image.content_type, disposition: 'inline'

See send_file for more information on HTTP Content-* headers and caching.

📝 Source code 
# File actionpack/lib/action_controller/metal/data_streaming.rb, line 111
      def send_data(data, options = {}) # :doc:
        send_file_headers! options
        render options.slice(:status, :content_type).merge(body: data)
      end
🔎 See on GitHub

send_file(path, options = {})

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.

📝 Source code 
# File actionpack/lib/action_controller/metal/data_streaming.rb, line 71
      def send_file(path, options = {}) # :doc:
        raise MissingFile, "Cannot read file #{path}" unless File.file?(path) && File.readable?(path)

        options[:filename] ||= File.basename(path) unless options[:url_based_filename]
        send_file_headers! options

        self.status = options[:status] || 200
        self.content_type = options[:content_type] if options.key?(:content_type)
        response.send_file path
      end
🔎 See on GitHub