require 'active_support/core_ext/array/extract_options'
require 'abstract_controller/collector'
module ActionController #:nodoc:
module MimeResponds
extend ActiveSupport::Concern
included do
class_attribute :responder, :mimes_for_respond_to
self.responder = ActionController::Responder
clear_respond_to
end
module ClassMethods
# Defines mime types that are rendered by default when invoking
# <tt>respond_with</tt>.
#
# respond_to :html, :xml, :json
#
# Specifies that all actions in the controller respond to requests
# for <tt>:html</tt>, <tt>:xml</tt> and <tt>:json</tt>.
#
# To specify on per-action basis, use <tt>:only</tt> and
# <tt>:except</tt> with an array of actions or a single action:
#
# respond_to :html
# respond_to :xml, :json, except: [ :edit ]
#
# This specifies that all actions respond to <tt>:html</tt>
# and all actions except <tt>:edit</tt> respond to <tt>:xml</tt> and
# <tt>:json</tt>.
#
# respond_to :json, only: :create
#
# This specifies that the <tt>:create</tt> action and no other responds
# to <tt>:json</tt>.
def respond_to(*mimes)
options = mimes.extract_options!
only_actions = Array(options.delete(:only)).map(&:to_s)
except_actions = Array(options.delete(:except)).map(&:to_s)
new = mimes_for_respond_to.dup
mimes.each do |mime|
mime = mime.to_sym
new[mime] = {}
new[mime][:only] = only_actions unless only_actions.empty?
new[mime][:except] = except_actions unless except_actions.empty?
end
self.mimes_for_respond_to = new.freeze
end
# Clear all mime types in <tt>respond_to</tt>.
#
def clear_respond_to
self.mimes_for_respond_to = Hash.new.freeze
end
end
# 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:
#
# <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
# 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
#
# Since this is a common pattern, you can use the class method respond_to
# with the respond_with method to have the same results:
#
# class PeopleController < ApplicationController
# respond_to :html, :xml, :json
#
# def index
# @people = Person.all
# respond_with(@people)
# end
# end
#
# Formats can have different variants.
#
# The request variant is a specialization of the request format, like <tt>:tablet</tt>,
# <tt>:phone</tt>, or <tt>:desktop<tt>.
#
# 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
#
# Be sure to check the documentation of +respond_with+ and
# <tt>ActionController::MimeResponds.respond_to</tt> for more examples.
def respond_to(*mimes, &block)
raise ArgumentError, "respond_to takes either types or a block, never both" if mimes.any? && block_given?
if collector = retrieve_collector_from_mimes(mimes, &block)
response = collector.response
response ? response.call : render({})
end
end
# For a given controller action, respond_with generates an appropriate
# response based on the mime-type requested by the client.
#
# If the method is called with just a resource, as in this example -
#
# class PeopleController < ApplicationController
# respond_to :html, :xml, :json
#
# def index
# @people = Person.all
# respond_with @people
# end
# end
#
# then the mime-type of the response is typically selected based on the
# request's Accept header and the set of available formats declared
# by previous calls to the controller's class method +respond_to+. Alternatively
# the mime-type can be selected by explicitly setting <tt>request.format</tt> in
# the controller.
#
# If an acceptable format is not identified, the application returns a
# '406 - not acceptable' status. Otherwise, the default response is to render
# a template named after the current action and the selected format,
# e.g. <tt>index.html.erb</tt>. If no template is available, the behavior
# depends on the selected format:
#
# * for an html response - if the request method is +get+, an exception
# is raised but for other requests such as +post+ the response
# depends on whether the resource has any validation errors (i.e.
# assuming that an attempt has been made to save the resource,
# e.g. by a +create+ action) -
# 1. If there are no errors, i.e. the resource
# was saved successfully, the response +redirect+'s to the resource
# i.e. its +show+ action.
# 2. If there are validation errors, the response
# renders a default action, which is <tt>:new</tt> for a
# +post+ request or <tt>:edit</tt> for +patch+ or +put+.
# Thus an example like this -
#
# respond_to :html, :xml
#
# def create
# @user = User.new(params[:user])
# flash[:notice] = 'User was successfully created.' if @user.save
# respond_with(@user)
# end
#
# is equivalent, in the absence of <tt>create.html.erb</tt>, to -
#
# def create
# @user = User.new(params[:user])
# respond_to do |format|
# if @user.save
# flash[:notice] = 'User was successfully created.'
# format.html { redirect_to(@user) }
# format.xml { render xml: @user }
# else
# format.html { render action: "new" }
# format.xml { render xml: @user }
# end
# end
# end
#
# * for a javascript request - if the template isn't found, an exception is
# raised.
# * for other requests - i.e. data formats such as xml, json, csv etc, if
# the resource passed to +respond_with+ responds to <code>to_<format></code>,
# the method attempts to render the resource in the requested format
# directly, e.g. for an xml request, the response is equivalent to calling
# <code>render xml: resource</code>.
#
# === Nested resources
#
# As outlined above, the +resources+ argument passed to +respond_with+
# can play two roles. It can be used to generate the redirect url
# for successful html requests (e.g. for +create+ actions when
# no template exists), while for formats other than html and javascript
# it is the object that gets rendered, by being converted directly to the
# required format (again assuming no template exists).
#
# For redirecting successful html requests, +respond_with+ also supports
# the use of nested resources, which are supplied in the same way as
# in <code>form_for</code> and <code>polymorphic_url</code>. For example -
#
# def create
# @project = Project.find(params[:project_id])
# @task = @project.comments.build(params[:task])
# flash[:notice] = 'Task was successfully created.' if @task.save
# respond_with(@project, @task)
# end
#
# This would cause +respond_with+ to redirect to <code>project_task_url</code>
# instead of <code>task_url</code>. For request formats other than html or
# javascript, if multiple resources are passed in this way, it is the last
# one specified that is rendered.
#
# === Customizing response behavior
#
# Like +respond_to+, +respond_with+ may also be called with a block that
# can be used to overwrite any of the default responses, e.g. -
#
# def create
# @user = User.new(params[:user])
# flash[:notice] = "User was successfully created." if @user.save
#
# respond_with(@user) do |format|
# format.html { render }
# end
# end
#
# The argument passed to the block is an ActionController::MimeResponds::Collector
# object which stores the responses for the formats defined within the
# block. Note that formats with responses defined explicitly in this way
# do not have to first be declared using the class method +respond_to+.
#
# Also, a hash passed to +respond_with+ immediately after the specified
# resource(s) is interpreted as a set of options relevant to all
# formats. Any option accepted by +render+ can be used, e.g.
# respond_with @people, status: 200
# However, note that these options are ignored after an unsuccessful attempt
# to save a resource, e.g. when automatically rendering <tt>:new</tt>
# after a post request.
#
# Two additional options are relevant specifically to +respond_with+ -
# 1. <tt>:location</tt> - overwrites the default redirect location used after
# a successful html +post+ request.
# 2. <tt>:action</tt> - overwrites the default render action used after an
# unsuccessful html +post+ request.
def respond_with(*resources, &block)
if self.class.mimes_for_respond_to.empty?
raise "In order to use respond_with, first you need to declare the " \
"formats your controller responds to in the class level."
end
if collector = retrieve_collector_from_mimes(&block)
options = resources.size == 1 ? {} : resources.extract_options!
options = options.clone
options[:default_response] = collector.response
(options.delete(:responder) || self.class.responder).call(self, resources, options)
end
end
protected
# Collect mimes declared in the class method respond_to valid for the
# current action.
def collect_mimes_from_class_level #:nodoc:
action = action_name.to_s
self.class.mimes_for_respond_to.keys.select do |mime|
config = self.class.mimes_for_respond_to[mime]
if config[:except]
!config[:except].include?(action)
elsif config[:only]
config[:only].include?(action)
else
true
end
end
end
# Returns a Collector object containing the appropriate mime-type response
# for the current request, based on the available responses defined by a block.
# In typical usage this is the block passed to +respond_with+ or +respond_to+.
#
# Sends :not_acceptable to the client and returns nil if no suitable format
# is available.
def retrieve_collector_from_mimes(mimes=nil, &block) #:nodoc:
mimes ||= collect_mimes_from_class_level
collector = Collector.new(mimes, request.variant)
block.call(collector) if block_given?
format = collector.negotiate_format(request)
if format
_process_format(format)
collector
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_with+ and +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
VariantFilter.new(@variant)
end
end
def response
response = @responses.fetch(format, @responses[Mime::ALL])
if response.is_a?(VariantFilter) || response.nil? || response.arity == 0
response
else
lambda { response.call VariantFilter.new(@variant) }
end
end
def negotiate_format(request)
@format = request.negotiate_mime(@responses.keys)
end
class VariantFilter #:nodoc:
def initialize(variant)
@variant = variant
end
def method_missing(name)
if block_given?
yield if name == @variant || (name == :none && @variant.nil?)
end
end
end
end
end
end
