require 'abstract_controller/collector' module ActionController #:nodoc: module MimeResponds # Without web-service support, an action which collects the data for displaying a list of people # might look something like this: # # def index # @people = Person.all # end # # Here's the same action, with web-service support baked in: # # def index # @people = Person.all # # respond_to do |format| # format.html # format.xml { render xml: @people } # end # end # # What that says is, "if the client wants HTML in response to this action, just respond as we # would have before, but if the client wants XML, return them the list of people in XML format." # (Rails determines the desired response format from the HTTP Accept header submitted by the client.) # # Supposing you have an action that adds a new person, optionally creating their company # (by name) if it does not already exist, without web-services, it might look like this: # # def create # @company = Company.find_or_create_by(name: params[:company][:name]) # @person = @company.people.create(params[:person]) # # redirect_to(person_list_url) # end # # Here's the same action, with web-service support baked in: # # def create # company = params[:person].delete(:company) # @company = Company.find_or_create_by(name: company[:name]) # @person = @company.people.create(params[:person]) # # respond_to do |format| # format.html { redirect_to(person_list_url) } # format.js # format.xml { render xml: @person.to_xml(include: @company) } # end # end # # If the client wants HTML, we just redirect them back to the person list. If they want JavaScript, # then it is an Ajax request and we render the JavaScript template associated with this action. # Lastly, if the client wants XML, we render the created person as XML, but with a twist: we also # include the person's company in the rendered XML, so you get something like this: # # # ... # ... # # ... # ... # ... # # # # Note, however, the extra bit at the top of that action: # # company = params[:person].delete(:company) # @company = Company.find_or_create_by(name: company[:name]) # # This is because the incoming XML document (if a web-service request is in process) can only contain a # single root-node. So, we have to rearrange things so that the request looks like this (url-encoded): # # person[name]=...&person[company][name]=...&... # # And, like this (xml-encoded): # # # ... # # ... # # # # In other words, we make the request so that it operates on a single entity's person. Then, in the action, # we extract the company data from the request, find or create the company, and then create the new person # with the remaining data. # # Note that you can define your own XML parameter parser which would allow you to describe multiple entities # in a single request (i.e., by wrapping them all in a single root node), but if you just go with the flow # and accept Rails' defaults, life will be much easier. # # If you need to use a MIME type which isn't supported by default, you can register your own handlers in # config/initializers/mime_types.rb as follows. # # Mime::Type.register "image/jpg", :jpg # # Respond to also allows you to specify a common block for different formats by using any: # # def index # @people = Person.all # # respond_to do |format| # format.html # format.any(:xml, :json) { render request.format.to_sym => @people } # end # end # # In the example above, if the format is xml, it will render: # # render xml: @people # # Or if the format is json: # # render json: @people # # Formats can have different variants. # # The request variant is a specialization of the request format, like :tablet, # :phone, or :desktop. # # We often want to render different html/json/xml templates for phones, # tablets, and desktop browsers. Variants make it easy. # # You can set the variant in a +before_action+: # # request.variant = :tablet if request.user_agent =~ /iPad/ # # Respond to variants in the action just like you respond to formats: # # respond_to do |format| # format.html do |variant| # variant.tablet # renders app/views/projects/show.html+tablet.erb # variant.phone { extra_setup; render ... } # variant.none { special_setup } # executed only if there is no variant set # end # end # # Provide separate templates for each format and variant: # # app/views/projects/show.html.erb # app/views/projects/show.html+tablet.erb # app/views/projects/show.html+phone.erb # # When you're not sharing any code within the format, you can simplify defining variants # using the inline syntax: # # respond_to do |format| # format.js { render "trash" } # format.html.phone { redirect_to progress_path } # format.html.none { render "trash" } # end # # Variants also support common `any`/`all` block that formats have. # # It works for both inline: # # respond_to do |format| # format.html.any { render html: "any" } # format.html.phone { render html: "phone" } # end # # and block syntax: # # respond_to do |format| # format.html do |variant| # variant.any(:tablet, :phablet){ render html: "any" } # variant.phone { render html: "phone" } # end # end # # You can also set an array of variants: # # request.variant = [:tablet, :phone] # # which will work similarly to formats and MIME types negotiation. If there will be no # :tablet variant declared, :phone variant will be picked: # # respond_to do |format| # format.html.none # format.html.phone # this gets rendered # end # # Be sure to check the documentation of ActionController::MimeResponds.respond_to # for more examples. def respond_to(*mimes) raise ArgumentError, "respond_to takes either types or a block, never both" if mimes.any? && block_given? collector = Collector.new(mimes, request.variant) yield collector if block_given? if format = collector.negotiate_format(request) _process_format(format) response = collector.response response ? response.call : render({}) else raise ActionController::UnknownFormat end end # A container for responses available from the current controller for # requests for different mime-types sent to a particular action. # # The public controller methods +respond_to+ may be called with a block # that is used to define responses to different mime-types, e.g. # for +respond_to+ : # # respond_to do |format| # format.html # format.xml { render xml: @people } # end # # In this usage, the argument passed to the block (+format+ above) is an # instance of the ActionController::MimeResponds::Collector class. This # object serves as a container in which available responses can be stored by # calling any of the dynamically generated, mime-type-specific methods such # as +html+, +xml+ etc on the Collector. Each response is represented by a # corresponding block if present. # # A subsequent call to #negotiate_format(request) will enable the Collector # to determine which specific mime-type it should respond with for the current # request, with this response then being accessible by calling #response. class Collector include AbstractController::Collector attr_accessor :format def initialize(mimes, variant = nil) @responses = {} @variant = variant mimes.each { |mime| @responses["Mime::#{mime.upcase}".constantize] = nil } end def any(*args, &block) if args.any? args.each { |type| send(type, &block) } else custom(Mime::ALL, &block) end end alias :all :any def custom(mime_type, &block) mime_type = Mime::Type.lookup(mime_type.to_s) unless mime_type.is_a?(Mime::Type) @responses[mime_type] ||= if block_given? block else VariantCollector.new(@variant) end end def response response = @responses.fetch(format, @responses[Mime::ALL]) if response.is_a?(VariantCollector) # `format.html.phone` - variant inline syntax response.variant elsif response.nil? || response.arity == 0 # `format.html` - just a format, call its block response else # `format.html{ |variant| variant.phone }` - variant block syntax variant_collector = VariantCollector.new(@variant) response.call(variant_collector) # call format block with variants collector variant_collector.variant end end def negotiate_format(request) @format = request.negotiate_mime(@responses.keys) end class VariantCollector #:nodoc: def initialize(variant = nil) @variant = variant @variants = {} end def any(*args, &block) if block_given? if args.any? && args.none?{ |a| a == @variant } args.each{ |v| @variants[v] = block } else @variants[:any] = block end end end alias :all :any def method_missing(name, *args, &block) @variants[name] = block if block_given? end def variant if @variant.empty? @variants[:none] || @variants[:any] else @variants[variant_key] end end private def variant_key @variant.find { |variant| @variants.key?(variant) } || :any end end end end end