module ActionDispatch::Http::MimeNegotiation - actionpack-4.2.4 Documentation

# module ActionDispatch::Http::MimeNegotiation

### Constants

BROWSER_LIKE_ACCEPTS

### Attributes

variant[R]

### Public Instance Methods

accepts() click to toggle source

Returns the accepted MIME type for the request.

    # File lib/action_dispatch/http/mime_negotiation.rb, line 34
    def accepts
      @env["action_dispatch.request.accepts"] ||= begin
        header = @env['HTTP_ACCEPT'].to_s.strip

        if header.empty?
          [content_mime_type]
        else
          Mime::Type.parse(header)
        end
      end
    end

content_mime_type() click to toggle source

The MIME type of the HTTP request, such as Mime::XML.

For backward compatibility, the post format is extracted from the X-Post-Data-Format HTTP header if present.

    # File lib/action_dispatch/http/mime_negotiation.rb, line 19
    def content_mime_type
      @env["action_dispatch.request.content_type"] ||= begin
        if @env['CONTENT_TYPE'] =~ /^([^,\;]*)/
          Mime::Type.lookup($1.strip.downcase)
        else
          nil
        end
      end
    end

content_type() click to toggle source

    # File lib/action_dispatch/http/mime_negotiation.rb, line 29
    def content_type
      content_mime_type && content_mime_type.to_s
    end

format(view_path = []) click to toggle source

Returns the MIME type for the format used in the request.

    GET /posts/5.xml   | request.format => Mime::XML
    GET /posts/5.xhtml | request.format => Mime::HTML
    GET /posts/5       | request.format => Mime::HTML or MIME::JS, or request.accepts.first

    # File lib/action_dispatch/http/mime_negotiation.rb, line 52
    def format(view_path = [])
      formats.first || Mime::NullType.instance
    end

format=(extension) click to toggle source

Sets the format by string extension, which can be used to force custom formats that are not controlled by the extension.

    class ApplicationController < ActionController::Base
      before_action :adjust_format_for_iphone

      private
        def adjust_format_for_iphone
          request.format = :iphone if request.env["HTTP_USER_AGENT"][/iPhone/]
        end
    end

    # File lib/action_dispatch/http/mime_negotiation.rb, line 101
    def format=(extension)
      parameters[:format] = extension.to_s
      @env["action_dispatch.request.formats"] = [Mime::Type.lookup_by_extension(parameters[:format])]
    end

formats() click to toggle source

    # File lib/action_dispatch/http/mime_negotiation.rb, line 56
    def formats
      @env["action_dispatch.request.formats"] ||= begin
        params_readable = begin
                            parameters[:format]
                          rescue ActionController::BadRequest
                            false
                          end

        if params_readable
          Array(Mime[parameters[:format]])
        elsif use_accept_header && valid_accept_header
          accepts
        elsif xhr?
          [Mime::JS]
        else
          [Mime::HTML]
        end
      end
    end

formats=(extensions) click to toggle source

Sets the formats by string extensions. This differs from format= by allowing you to set multiple, ordered formats, which is useful when you want to have a fallback.

In this example, the :iphone format will be used if it's available, otherwise it'll fallback to the :html format.

    class ApplicationController < ActionController::Base
      before_action :adjust_format_for_iphone_with_html_fallback

      private
        def adjust_format_for_iphone_with_html_fallback
          request.formats = [ :iphone, :html ] if request.env["HTTP_USER_AGENT"][/iPhone/]
        end
    end

    # File lib/action_dispatch/http/mime_negotiation.rb, line 120
    def formats=(extensions)
      parameters[:format] = extensions.first.to_s
      @env["action_dispatch.request.formats"] = extensions.collect do |extension|
        Mime::Type.lookup_by_extension(extension)
      end
    end

negotiate_mime(order) click to toggle source

Receives an array of mimes and return the first user sent mime that matches the order array.

    # File lib/action_dispatch/http/mime_negotiation.rb, line 130
    def negotiate_mime(order)
      formats.each do |priority|
        if priority == Mime::ALL
          return order.first
        elsif order.include?(priority)
          return priority
        end
      end

      order.include?(Mime::ALL) ? format : nil
    end

variant=(variant) click to toggle source

Sets the variant for template.

    # File lib/action_dispatch/http/mime_negotiation.rb, line 77
    def variant=(variant)
      if variant.is_a?(Symbol)
        @variant = [variant]
      elsif variant.nil? || variant.is_a?(Array) && variant.any? && variant.all?{ |v| v.is_a?(Symbol) }
        @variant = variant
      else
        raise ArgumentError, "request.variant must be set to a Symbol or an Array of Symbols, not a #{variant.class}. "              "For security reasons, never directly set the variant to a user-provided value, "              "like params[:variant].to_sym. Check user-provided value against a whitelist first, "              "then set the variant: request.variant = :tablet if params[:variant] == 'tablet'"
      end
    end

### Protected Instance Methods

use_accept_header() click to toggle source

    # File lib/action_dispatch/http/mime_negotiation.rb, line 151
    def use_accept_header
      !self.class.ignore_accept_header
    end

valid_accept_header() click to toggle source

    # File lib/action_dispatch/http/mime_negotiation.rb, line 146
    def valid_accept_header
      (xhr? && (accept.present? || content_mime_type)) ||
        (accept.present? && accept !~ BROWSER_LIKE_ACCEPTS)
    end