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Constants

BROWSER_LIKE_ACCEPTS = /,\s*\*\/\*|\*\/\*\s*,/
 

We use normal content negotiation unless you include / in your list, in which case we assume you're a browser and send HTML.

RESCUABLE_MIME_FORMAT_ERRORS = [ ActionController::BadRequest, ActionDispatch::Http::Parameters::ParseError, ]
 

Instance Public methods

accepts()

Returns the accepted MIME type for the request.

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 54
def accepts
  fetch_header("action_dispatch.request.accepts") do |k|
    header = get_header("HTTP_ACCEPT").to_s.strip

    v = if header.empty?
      [content_mime_type]
    else
      Mime::Type.parse(header)
    end
    set_header k, v
  rescue ::Mime::Type::InvalidMimeType => e
    raise InvalidType, e.message
  end
end

content_mime_type()

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

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 23
def content_mime_type
  fetch_header("action_dispatch.request.content_type") do |k|
    v = if get_header("CONTENT_TYPE") =~ /^([^,;]*)/
      Mime::Type.lookup($1.strip.downcase)
    else
      nil
    end
    set_header k, v
  rescue ::Mime::Type::InvalidMimeType => e
    raise InvalidType, e.message
  end
end

content_type()

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 36
def content_type
  if self.class.return_only_media_type_on_content_type
    ActiveSupport::Deprecation.warn(
      "Rails 7.1 will return Content-Type header without modification." \
      " If you want just the MIME type, please use `#media_type` instead."
    )

    content_mime_type&.to_s
  else
    super
  end
end

format(view_path = [])

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 actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 75
def format(view_path = [])
  formats.first || Mime::NullType.instance
end

format=(extension)

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 actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 127
def format=(extension)
  parameters[:format] = extension.to_s
  set_header "action_dispatch.request.formats", [Mime::Type.lookup_by_extension(parameters[:format])]
end

formats()

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 79
def formats
  fetch_header("action_dispatch.request.formats") do |k|
    v = if params_readable?
      Array(Mime[parameters[:format]])
    elsif use_accept_header && valid_accept_header
      accepts
    elsif extension_format = format_from_path_extension
      [extension_format]
    elsif xhr?
      [Mime[:js]]
    else
      [Mime[:html]]
    end

    v = v.select do |format|
      format.symbol || format.ref == "*/*"
    end

    set_header k, v
  end
end

formats=(extensions)

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 actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 146
def formats=(extensions)
  parameters[:format] = extensions.first.to_s
  set_header "action_dispatch.request.formats", extensions.collect { |extension|
    Mime::Type.lookup_by_extension(extension)
  }
end

negotiate_mime(order)

Returns the first MIME type that matches the provided array of MIME types.

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 154
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

should_apply_vary_header?()

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 166
def should_apply_vary_header?
  !params_readable? && use_accept_header && valid_accept_header
end

variant()

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 112
def variant
  @variant ||= ActiveSupport::ArrayInquirer.new
end

variant=(variant)

Sets the variant for template.

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 102
def variant=(variant)
  variant = Array(variant)

  if variant.all?(Symbol)
    @variant = ActiveSupport::ArrayInquirer.new(variant)
  else
    raise ArgumentError, "request.variant must be set to a Symbol or an Array of Symbols."
  end
end

Instance Private methods

format_from_path_extension()

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 190
def format_from_path_extension # :doc:
  path = get_header("action_dispatch.original_path") || get_header("PATH_INFO")
  if match = path && path.match(/\.(\w+)\z/)
    Mime[match.captures.first]
  end
end

params_readable?()

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 175
def params_readable? # :doc:
  parameters[:format]
rescue *RESCUABLE_MIME_FORMAT_ERRORS
  false
end

use_accept_header()

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 186
def use_accept_header # :doc:
  !self.class.ignore_accept_header
end

valid_accept_header()

# File actionpack/lib/action_dispatch/http/mime_negotiation.rb, line 181
def valid_accept_header # :doc:
  (xhr? && (accept.present? || content_mime_type)) ||
    (accept.present? && !accept.match?(BROWSER_LIKE_ACCEPTS))
end