Render without calling the controller's action in Merb

I was working on a Merb project in the company, I found a common request is generate the report to view in the browser and also send the report as an attachment of an email in a cron job. Usually I have to do two parts of job, one is for the regular MVC parts to get the report in a browser. Then I have to generate the report and write it a file(html, text or pdf). Then send it out later. As you might see, there is a duplication here, I have to design the report twice. This really bothered me, why can't I just re-use the view templates which is used in the MVC. After poking around the merb-core source files, it turns out pretty easy to do that:

	def generate_daily_pos_report
	# create a fake request
	fake_request = Merb::Request.new({})
	# init the controller
	controller = Purchasing::Reports.new(fake_request)
	# gets all the pos created on today
	pos = PurchaseOrder.all(:deleted => false, :po_date => date)
	results = "No purchase orders created on #{date}"
	if pos.size > 0
	## set the instance varialbe for the html.erb, :@pos see report/deaily_pos.html.erb
	controller.instance_variable_set(:@pos, pos)
	# gets the html string
	results = controller.render :_daily_pos_results, :layout => :email
	end
	# if you want to re-use the logic in controll, you have to use _dispatch
	# but this is not a good solution, you have embed in some extra logic to
	# handle the render method in controller, the best way to re-use the logic
	# in controller is to move the logic out of controller, put it some services
	# layer, then you can re-use it.
	# result = controller._dispatch(:daily_pos)
	file = purchasing_dir + "/#{date}.html"
	File.open(file, 'w') {|f| f.puts results}
	file
	end

view raw calling_render.rb hosted with ❤ by GitHub

This is another reason I love Merb.