module ActionController #:nodoc:
module MimeResponds #:nodoc:
# 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.find(:all)
# end
#
# Here's the same action, with web-service support baked in:
#
# def index
# @people = Person.find(:all)
#
# respond_to do |format|
# format.html
# format.xml { render :xml => @people.to_xml }
# 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
# (format.js), then it is an RJS request and we render the RJS 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:
#
# <person>
# <id>...</id>
# ...
# <company>
# <id>...</id>
# <name>...</name>
# ...
# </company>
# </person>
#
# 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):
#
# <person>
# <name>...</name>
# <company>
# <name>...</name>
# </company>
# </person>
#
# 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
# environment.rb as follows.
#
# Mime::Type.register "image/jpg", :jpg
def respond_to(*mimes, &block)
raise ArgumentError, "respond_to takes either types or a block, never both" unless mimes.any? ^ block
responder = Responder.new(request.formats)
if block_given?
block.call(responder)
else
mimes.each { |mime| responder.send(mime) }
end
mime = responder.respond
if mime
self.formats = [mime.to_sym]
self.content_type = mime
self.template.formats = [mime.to_sym]
if response = responder.response_for(mime)
response.call
else
default_render
end
else
head :not_acceptable
end
end
class Responder #:nodoc:
def initialize(priorities)
@mime_type_priority = priorities
@order, @responses = [], {}
end
def any(*args, &block)
if args.any?
args.each { |type| send(type, &block) }
else
custom(@mime_type_priority.first, &block)
end
end
def custom(mime_type, &block)
mime_type = mime_type.is_a?(Mime::Type) ? mime_type : Mime::Type.lookup(mime_type.to_s)
@order << mime_type
@responses[mime_type] ||= block
end
def respond
available_mimes.first
end
def response_for(mime)
@responses[mime]
end
# Compares mimes sent by the client (@mime_type_priorities) with the ones
# that the user configured in the controller respond_to. Returns them
# all in an array.
#
def available_mimes
mimes = []
@mime_type_priority.each do |priority|
if priority == Mime::ALL
mimes << @order.first unless mimes.include?(@order.first)
elsif @order.include?(priority)
mimes << priority
end
end
mimes << Mime::ALL if @order.include?(Mime::ALL)
mimes
end
protected
def method_missing(symbol, &block)
mime_constant = Mime.const_get(symbol.to_s.upcase)
if Mime::SET.include?(mime_constant)
generate_method_for_mime(mime_constant)
send(symbol, &block)
else
super
end
end
def generate_method_for_mime(mime)
sym = mime.is_a?(Symbol) ? mime : mime.to_sym
const = sym.to_s.upcase
class_eval <<-RUBY, __FILE__, __LINE__ + 1
def #{sym}(&block) # def html(&block)
custom(Mime::#{const}, &block) # custom(Mime::HTML, &block)
end # end
RUBY
end
end
end
end
