module ActionController #:nodoc:
module MimeResponds #:nodoc:
def self.included(base)
base.send(:include, ActionController::MimeResponds::InstanceMethods)
end
module InstanceMethods
# Without web-service support, an action which collects the data for displaying a list of people
# might look something like this:
#
# def list
# @people = Person.find(:all)
# end
#
# Here's the same action, with web-service support baked in:
#
# def list
# @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 add
# @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 add
# 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
# (wants.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—a 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 note), 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(*types, &block)
raise ArgumentError, "respond_to takes either types or a block, never both" unless types.any? ^ block
block ||= lambda { |responder| types.each { |type| responder.send(type) } }
responder = Responder.new(block.binding)
block.call(responder)
responder.respond
end
end
class Responder #:nodoc:
DEFAULT_BLOCKS = [:html, :js, :xml].inject({}) do |blocks, ext|
blocks.update ext => %(Proc.new { render :action => "\#{action_name}.r#{ext}" })
end
def initialize(block_binding)
@block_binding = block_binding
@mime_type_priority = eval(
"(params[:format] && Mime::EXTENSION_LOOKUP[params[:format]]) ? " +
"[ Mime::EXTENSION_LOOKUP[params[:format]] ] : request.accepts",
block_binding
)
@order = []
@responses = {}
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
if block_given?
@responses[mime_type] = block
else
if source = DEFAULT_BLOCKS[mime_type.to_sym]
@responses[mime_type] = eval(source, @block_binding)
else
raise ActionController::RenderError, "Expected a block but none was given for custom mime handler #{mime_type}"
end
end
end
def any(*args, &block)
args.each { |type| send(type, &block) }
end
def method_missing(symbol, &block)
mime_constant = symbol.to_s.upcase
if Mime::SET.include?(Mime.const_get(mime_constant))
custom(Mime.const_get(mime_constant), &block)
else
super
end
end
def respond
for priority in @mime_type_priority
if priority == Mime::ALL
@responses[@order.first].call
return
else
if priority === @order
@responses[priority].call
return # mime type match found, be happy and return
end
end
end
if @order.include?(Mime::ALL)
@responses[Mime::ALL].call
else
eval 'render(:nothing => true, :status => "406 Not Acceptable")', @block_binding
end
end
end
end
end
