Small library on top of wkthmltopdf + pdfkit (https://github.com/pdfkit/pdfkit) so e.g. app/models/foo_document.rb can render from app/views/documents/foo_document.html.slim and use partials etc.

base_document.rb

class BaseDocument
  pattr_initialize :data

  def to_pdf
    PDFKit.new(to_html).to_pdf
  end

  def to_html
    BaseDocument::TemplateRenderer.new(
      template_name, data
    ).to_html
  end

  private

  # E.g. TestDocument -> test_document.
  def template_name
    self.class.name.underscore
  end
end

class BaseDocument
  class TemplateRenderer < AbstractController::Base
    include AbstractController::Rendering

    self.view_paths = "app/views/documents"
    pattr_initialize :template_name, :data

    # E.g. `render "my_partial"` will look for
    # "#{view_paths}/#{controller_path}/my_partial".
    def controller_path
      template_name
    end

    def to_html
      render template: template_name, locals: data
    end
  end
end