Question

I would love to call a controller action from within a model. Yes, MVC. Thanks.

So, why would i like to call a controller action and fetch the response?

Because my controller knows how to render the file I would like to cache. Why should I duplicate code to collect all data needed by my view?

Setup:

• InvoicesController responds_to :html, :pdf
• Invoice uses state_machine (:new -> :open -> paid)

What I “need” within the state transition from :new to :open

• generate /invoices/:id.pdf
• cache the PDF as Invoice#file for later use in delayed_job or simliar

What interface i would love to use elsewhere?

• @invoice.build_pdf

Any suggestions?

Update:
I would like to cache the PDF as model attachement for later use (delayed_job mailing, etc)

Answer 1

It may be better to take the code you’re using in your controller to render the PDF data, and create a module or class in your lib directory let’s say lib/pdf.rb then use that code in both your controller and your model.

Update: You can cache the PDF itself on the filesystem as a file with a timestamp as it’s name or something like that that is uniquely identifiable. Then add a file or invoice attribute to the model to store the location in the database for later use.

Update: You can use the block form of respond_to like so:

respond_to do |format|
  format.html
  format.pdf  { InvoiceBuilder.create(@invoice) }
end

Update: It seems that ActionDispatch::Integration::Session is a class for creating and interface for integration testing. But I think you could exploit it for your purposes.
You should be able to use it like this:

# app/models/invoice.rb
class Invoice < ActiveRecord::Base
  def get_body
    app = ActionDispatch::Integration::Session.new(Rails.application)
    app.get("invoices/#{self.id}.pdf")
    app.response.body # this returns the rendered content that the browser will see.
  end
end

Another way would be to grab the content by using curl i.e. curl http://localhost:3000/invoices/1.pdf and store the output.