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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_for_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
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