module ActionController::DataStreaming - actionpack-4.2.3 Documentation

# module ActionController::DataStreaming

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

### Protected Instance Methods

send_data(data, options = {}) click to toggle source

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 apparent 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 register with `Mime::Type.register`, for example :json If omitted, type will be guessed from the file extension specified in `:filename`. If no content type is registered for the extension, 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.

    # File lib/action_controller/metal/data_streaming.rb, line 127
    def send_data(data, options = {}) #:doc:
      send_file_headers! options
      render options.slice(:status, :content_type).merge(:text => data)
    end

send_file(path, options = {}) click to toggle source

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 register with `Mime::Type.register`, for example :json If omitted, type will be guessed from the file extension specified in `:filename`. If no content type is registered for the extension, 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 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', status: 404

Read about the other Content-* HTTP headers if you'd like to provide the user with more information (such as Content-Description) in www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.11.

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 www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9 for the Cache-Control header spec.

    # File lib/action_controller/metal/data_streaming.rb, line 67
    def send_file(path, options = {}) #:doc:
      raise MissingFile, "Cannot read file #{path}" unless File.file?(path) and 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)
      self.response_body = FileBody.new(path)
    end

### Private Instance Methods

send_file_headers!(options) click to toggle source

    # File lib/action_controller/metal/data_streaming.rb, line 133
    def send_file_headers!(options)
      type_provided = options.has_key?(:type)

      content_type = options.fetch(:type, DEFAULT_SEND_FILE_TYPE)
      raise ArgumentError, ":type option required" if content_type.nil?

      if content_type.is_a?(Symbol)
        extension = Mime[content_type]
        raise ArgumentError, "Unknown MIME type #{options[:type]}" unless extension
        self.content_type = extension
      else
        if !type_provided && options[:filename]
          # If type wasn't provided, try guessing from file extension.
          content_type = Mime::Type.lookup_by_extension(File.extname(options[:filename]).downcase.delete('.')) || content_type
        end
        self.content_type = content_type
      end

      disposition = options.fetch(:disposition, DEFAULT_SEND_FILE_DISPOSITION)
      unless disposition.nil?
        disposition  = disposition.to_s
        disposition += %Q(; filename="#{options[:filename]}") if options[:filename]
        headers['Content-Disposition'] = disposition
      end

      headers['Content-Transfer-Encoding'] = 'binary'

      response.sending_file = true

      # Fix a problem with IE 6.0 on opening downloaded files:
      # If Cache-Control: no-cache is set (which Rails does by default),
      # IE removes the file it just downloaded from its cache immediately
      # after it displays the "open/save" dialog, which means that if you
      # hit "open" the file isn't there anymore when the application that
      # is called for handling the download is run, so let's workaround that
      response.cache_control[:public] ||= false
    end