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9d9cc4777b
Closes #18933.
305 lines
10 KiB
Ruby
305 lines
10 KiB
Ruby
require 'abstract_controller/collector'
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module ActionController #:nodoc:
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module MimeResponds
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# Without web-service support, an action which collects the data for displaying a list of people
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# might look something like this:
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#
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# def index
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# @people = Person.all
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# end
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#
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# Here's the same action, with web-service support baked in:
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#
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# def index
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# @people = Person.all
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#
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# respond_to do |format|
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# format.html
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# format.xml { render xml: @people }
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# end
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# end
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#
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# What that says is, "if the client wants HTML in response to this action, just respond as we
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# would have before, but if the client wants XML, return them the list of people in XML format."
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# (Rails determines the desired response format from the HTTP Accept header submitted by the client.)
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#
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# Supposing you have an action that adds a new person, optionally creating their company
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# (by name) if it does not already exist, without web-services, it might look like this:
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#
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# def create
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# @company = Company.find_or_create_by(name: params[:company][:name])
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# @person = @company.people.create(params[:person])
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#
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# redirect_to(person_list_url)
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# end
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#
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# Here's the same action, with web-service support baked in:
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#
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# def create
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# company = params[:person].delete(:company)
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# @company = Company.find_or_create_by(name: company[:name])
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# @person = @company.people.create(params[:person])
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#
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# respond_to do |format|
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# format.html { redirect_to(person_list_url) }
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# format.js
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# format.xml { render xml: @person.to_xml(include: @company) }
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# end
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# end
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#
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# If the client wants HTML, we just redirect them back to the person list. If they want JavaScript,
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# then it is an Ajax request and we render the JavaScript template associated with this action.
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# Lastly, if the client wants XML, we render the created person as XML, but with a twist: we also
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# include the person's company in the rendered XML, so you get something like this:
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#
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# <person>
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# <id>...</id>
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# ...
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# <company>
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# <id>...</id>
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# <name>...</name>
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# ...
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# </company>
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# </person>
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#
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# Note, however, the extra bit at the top of that action:
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#
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# company = params[:person].delete(:company)
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# @company = Company.find_or_create_by(name: company[:name])
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#
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# This is because the incoming XML document (if a web-service request is in process) can only contain a
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# single root-node. So, we have to rearrange things so that the request looks like this (url-encoded):
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#
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# person[name]=...&person[company][name]=...&...
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#
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# And, like this (xml-encoded):
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#
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# <person>
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# <name>...</name>
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# <company>
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# <name>...</name>
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# </company>
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# </person>
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#
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# In other words, we make the request so that it operates on a single entity's person. Then, in the action,
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# we extract the company data from the request, find or create the company, and then create the new person
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# with the remaining data.
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#
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# Note that you can define your own XML parameter parser which would allow you to describe multiple entities
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# in a single request (i.e., by wrapping them all in a single root node), but if you just go with the flow
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# and accept Rails' defaults, life will be much easier.
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#
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# If you need to use a MIME type which isn't supported by default, you can register your own handlers in
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# config/initializers/mime_types.rb as follows.
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#
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# Mime::Type.register "image/jpg", :jpg
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#
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# Respond to also allows you to specify a common block for different formats by using any:
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#
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# def index
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# @people = Person.all
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#
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# respond_to do |format|
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# format.html
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# format.any(:xml, :json) { render request.format.to_sym => @people }
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# end
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# end
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#
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# In the example above, if the format is xml, it will render:
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#
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# render xml: @people
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#
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# Or if the format is json:
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#
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# render json: @people
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#
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# Formats can have different variants.
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#
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# The request variant is a specialization of the request format, like <tt>:tablet</tt>,
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# <tt>:phone</tt>, or <tt>:desktop</tt>.
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#
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# We often want to render different html/json/xml templates for phones,
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# tablets, and desktop browsers. Variants make it easy.
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#
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# You can set the variant in a +before_action+:
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#
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# request.variant = :tablet if request.user_agent =~ /iPad/
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#
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# Respond to variants in the action just like you respond to formats:
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#
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# respond_to do |format|
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# format.html do |variant|
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# variant.tablet # renders app/views/projects/show.html+tablet.erb
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# variant.phone { extra_setup; render ... }
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# variant.none { special_setup } # executed only if there is no variant set
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# end
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# end
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#
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# Provide separate templates for each format and variant:
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#
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# app/views/projects/show.html.erb
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# app/views/projects/show.html+tablet.erb
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# app/views/projects/show.html+phone.erb
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#
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# When you're not sharing any code within the format, you can simplify defining variants
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# using the inline syntax:
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#
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# respond_to do |format|
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# format.js { render "trash" }
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# format.html.phone { redirect_to progress_path }
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# format.html.none { render "trash" }
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# end
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#
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# Variants also support common `any`/`all` block that formats have.
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#
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# It works for both inline:
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#
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# respond_to do |format|
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# format.html.any { render text: "any" }
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# format.html.phone { render text: "phone" }
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# end
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#
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# and block syntax:
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#
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# respond_to do |format|
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# format.html do |variant|
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# variant.any(:tablet, :phablet){ render text: "any" }
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# variant.phone { render text: "phone" }
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# end
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# end
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#
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# You can also set an array of variants:
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#
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# request.variant = [:tablet, :phone]
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#
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# which will work similarly to formats and MIME types negotiation. If there will be no
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# :tablet variant declared, :phone variant will be picked:
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#
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# respond_to do |format|
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# format.html.none
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# format.html.phone # this gets rendered
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# end
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#
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# Be sure to check the documentation of <tt>ActionController::MimeResponds.respond_to</tt>
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# for more examples.
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def respond_to(*mimes)
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raise ArgumentError, "respond_to takes either types or a block, never both" if mimes.any? && block_given?
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collector = Collector.new(mimes, request.variant)
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yield collector if block_given?
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if format = collector.negotiate_format(request)
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_process_format(format)
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response = collector.response
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response ? response.call : render({})
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else
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raise ActionController::UnknownFormat
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end
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end
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# A container for responses available from the current controller for
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# requests for different mime-types sent to a particular action.
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#
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# The public controller methods +respond_to+ may be called with a block
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# that is used to define responses to different mime-types, e.g.
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# for +respond_to+ :
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#
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# respond_to do |format|
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# format.html
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# format.xml { render xml: @people }
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# end
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#
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# In this usage, the argument passed to the block (+format+ above) is an
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# instance of the ActionController::MimeResponds::Collector class. This
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# object serves as a container in which available responses can be stored by
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# calling any of the dynamically generated, mime-type-specific methods such
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# as +html+, +xml+ etc on the Collector. Each response is represented by a
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# corresponding block if present.
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#
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# A subsequent call to #negotiate_format(request) will enable the Collector
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# to determine which specific mime-type it should respond with for the current
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# request, with this response then being accessible by calling #response.
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class Collector
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include AbstractController::Collector
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attr_accessor :format
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def initialize(mimes, variant = nil)
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@responses = {}
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@variant = variant
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mimes.each { |mime| @responses["Mime::#{mime.upcase}".constantize] = nil }
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end
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def any(*args, &block)
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if args.any?
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args.each { |type| send(type, &block) }
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else
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custom(Mime::ALL, &block)
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end
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end
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alias :all :any
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def custom(mime_type, &block)
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mime_type = Mime::Type.lookup(mime_type.to_s) unless mime_type.is_a?(Mime::Type)
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@responses[mime_type] ||= if block_given?
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block
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else
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VariantCollector.new(@variant)
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end
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end
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def response
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response = @responses.fetch(format, @responses[Mime::ALL])
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if response.is_a?(VariantCollector) # `format.html.phone` - variant inline syntax
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response.variant
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elsif response.nil? || response.arity == 0 # `format.html` - just a format, call its block
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response
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else # `format.html{ |variant| variant.phone }` - variant block syntax
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variant_collector = VariantCollector.new(@variant)
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response.call(variant_collector) # call format block with variants collector
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variant_collector.variant
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end
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end
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def negotiate_format(request)
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@format = request.negotiate_mime(@responses.keys)
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end
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class VariantCollector #:nodoc:
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def initialize(variant = nil)
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@variant = variant
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@variants = {}
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end
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def any(*args, &block)
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if block_given?
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if args.any? && args.none?{ |a| a == @variant }
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args.each{ |v| @variants[v] = block }
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else
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@variants[:any] = block
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end
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end
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end
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alias :all :any
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def method_missing(name, *args, &block)
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@variants[name] = block if block_given?
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end
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def variant
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if @variant.empty?
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@variants[:none] || @variants[:any]
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else
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@variants[variant_key]
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end
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end
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private
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def variant_key
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@variant.find { |variant| @variants.key?(variant) } || :any
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end
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end
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end
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end
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end
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