module ActionController #:nodoc: # Components allow you to call other actions for their rendered response while executing another action. You can either delegate # the entire response rendering or you can mix a partial response in with your other content. # # class WeblogController < ActionController::Base # # Performs a method and then lets hello_world output its render # def delegate_action # do_other_stuff_before_hello_world # render_component :controller => "greeter", :action => "hello_world", :params => { :person => "david" } # end # end # # class GreeterController < ActionController::Base # def hello_world # render :text => "#{params[:person]} says, Hello World!" # end # end # # The same can be done in a view to do a partial rendering: # # Let's see a greeting: # <%= render_component :controller => "greeter", :action => "hello_world" %> # # It is also possible to specify the controller as a class constant, bypassing the inflector # code to compute the controller class at runtime: # # <%= render_component :controller => GreeterController, :action => "hello_world" %> # # == When to use components # # Components should be used with care. They're significantly slower than simply splitting reusable parts into partials and # conceptually more complicated. Don't use components as a way of separating concerns inside a single application. Instead, # reserve components to those rare cases where you truly have reusable view and controller elements that can be employed # across many applications at once. # # So to repeat: Components are a special-purpose approach that can often be replaced with better use of partials and filters. module Components def self.included(base) #:nodoc: base.send :include, InstanceMethods base.extend(ClassMethods) base.helper do def render_component(options) @controller.send(:render_component_as_string, options) end end # If this controller was instantiated to process a component request, # +parent_controller+ points to the instantiator of this controller. base.send :attr_accessor, :parent_controller base.class_eval do alias_method_chain :process_cleanup, :components alias_method_chain :set_session_options, :components alias_method_chain :flash, :components alias_method :component_request?, :parent_controller end end module ClassMethods # Track parent controller to identify component requests def process_with_components(request, response, parent_controller = nil) #:nodoc: controller = new controller.parent_controller = parent_controller controller.process(request, response) end end module InstanceMethods # Extracts the action_name from the request parameters and performs that action. def process_with_components(request, response, method = :perform_action, *arguments) #:nodoc: flash.discard if component_request? process_without_components(request, response, method, *arguments) end protected # Renders the component specified as the response for the current method def render_component(options) #:doc: component_logging(options) do render_text(component_response(options, true).body, response.headers["Status"]) end end # Returns the component response as a string def render_component_as_string(options) #:doc: component_logging(options) do response = component_response(options, false) if redirected = response.redirected_to render_component_as_string(redirected) else response.body end end end def flash_with_components(refresh = false) #:nodoc: if !defined?(@_flash) || refresh @_flash = if defined?(@parent_controller) @parent_controller.flash else flash_without_components end end @_flash end private def component_response(options, reuse_response) klass = component_class(options) request = request_for_component(klass.controller_name, options) new_response = reuse_response ? response : response.dup klass.process_with_components(request, new_response, self) end # determine the controller class for the component request def component_class(options) if controller = options[:controller] controller.is_a?(Class) ? controller : "#{controller.camelize}Controller".constantize else self.class end end # Create a new request object based on the current request. # The new request inherits the session from the current request, # bypassing any session options set for the component controller's class def request_for_component(controller_name, options) new_request = request.dup new_request.session = request.session new_request.instance_variable_set( :@parameters, (options[:params] || {}).with_indifferent_access.update( "controller" => controller_name, "action" => options[:action], "id" => options[:id] ) ) new_request end def component_logging(options) if logger logger.info "Start rendering component (#{options.inspect}): " result = yield logger.info "\n\nEnd of component rendering" result else yield end end def set_session_options_with_components(request) set_session_options_without_components(request) unless component_request? end def process_cleanup_with_components process_cleanup_without_components unless component_request? end end end end