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# frozen_string_literal: true
require "abstract_controller/collector"
module ActionController #:nodoc:
module MimeResponds
# 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
#
# That action implicitly responds to all formats, but formats can also be whitelisted:
#
# def index
# @people = Person.all
# respond_to :html, :js
# end
#
# Here's the same action, with web-service support baked in:
#
# def index
# @people = Person.all
#
# respond_to do |format|
# format.html
# format.js
# format.xml { render xml: @people }
# end
# end
#
# What that says is, "if the client wants HTML or JS 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
#
# 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
#
# When you're not sharing any code within the format, you can simplify defining variants
# using the inline syntax:
#
# respond_to do |format|
# format.js { render "trash" }
# format.html.phone { redirect_to progress_path }
# format.html.none { render "trash" }
# end
#
# Variants also support common +any+/+all+ block that formats have.
#
# It works for both inline:
#
# respond_to do |format|
# format.html.any { render html: "any" }
# format.html.phone { render html: "phone" }
# end
#
# and block syntax:
#
# respond_to do |format|
# format.html do |variant|
# variant.any(:tablet, :phablet){ render html: "any" }
# variant.phone { render html: "phone" }
# end
# end
#
# You can also set an array of variants:
#
# request.variant = [:tablet, :phone]
#
# This will work similarly to formats and MIME types negotiation. If there
# is no +:tablet+ variant declared, the +:phone+ variant will be used:
#
# respond_to do |format|
# format.html.none
# format.html.phone # this gets rendered
# end
def respond_to(*mimes)
raise ArgumentError, "respond_to takes either types or a block, never both" if mimes.any? && block_given?
collector = Collector.new(mimes, request.variant)
yield collector if block_given?
if format = collector.negotiate_format(request)
_process_format(format)
_set_rendered_content_type format
response = collector.response
response.call if response
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_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]] = 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
VariantCollector.new(@variant)
end
end
def response
response = @responses.fetch(format, @responses[Mime::ALL])
if response.is_a?(VariantCollector) # `format.html.phone` - variant inline syntax
response.variant
elsif response.nil? || response.arity == 0 # `format.html` - just a format, call its block
response
else # `format.html{ |variant| variant.phone }` - variant block syntax
variant_collector = VariantCollector.new(@variant)
response.call(variant_collector) # call format block with variants collector
variant_collector.variant
end
end
def negotiate_format(request)
@format = request.negotiate_mime(@responses.keys)
end
class VariantCollector #:nodoc:
def initialize(variant = nil)
@variant = variant
@variants = {}
end
def any(*args, &block)
if block_given?
if args.any? && args.none? { |a| a == @variant }
args.each { |v| @variants[v] = block }
else
@variants[:any] = block
end
end
end
alias :all :any
def method_missing(name, *args, &block)
@variants[name] = block if block_given?
end
def variant
if @variant.empty?
@variants[:none] || @variants[:any]
else
@variants[variant_key]
end
end
private
def variant_key
@variant.find { |variant| @variants.key?(variant) } || :any
end
end
end
end
end