CableCar template renderer

cable_car_template.rb

# frozen_string_literal: true

class CableCarTemplate
  attr_accessor :source

  def initialize(&block)
    self.source = block
  end

  def render_in(view_context)
    source.call
    view_context.controller.render(
      cable_ready: view_context.cable_car
    )
  end

  def format
    :json
  end

  def self.call(template, source = nil)
    src = source || template.source
    <<~RUBY
      __cablecar_template__ = CableCarTemplate.new do
        #{src}
      end
      __cablecar_template__.render_in(self).to_s
    RUBY
  end
end

example.cable_ready.cablecar

# frozen_string_literal: true

dialog_id = dom_id(@organization_deal, :new_update)

html_string = controller.render_to_string(ExampleComponent.new(
  open: true,
  id: dialog_id
))

cable_car.append(
  html: html_string,
  selector: "#example",
)

railtie.rb

## ...

initializer("cable_ready.template_renderer") do
  ActiveSupport.on_load :action_view do
    ActionView::Template.register_template_handler :cablecar, CableCarTemplate
  end
end

• To try to clean up controllers, keep it lean, handle a variety
  of rendering variants/complexity, and fit into the larger Rails
  MVC flow; we should have a template handler for CableReady
• CableCarTemplate uses Rails' render_in support to render the
  object using the given view_context.
  • Instances of the object require a block to be given, which acts as
    the source of the template
  • When render_in is called, we make sure to call the source so
    that it is evaluated, then we reach back into the view context's
    controller to use the predefined renderer from CableReady, to
    keep in line with the main app itself
• The CableCarTemplate.call method takes in the template/source,
  coalesces it into a src that we can pass into an instance of
  CableCarTemplate, which we then call render_in using the
  ActionView context
• The handler is registered as :cablecar, so the file format would
  be [template].cable_ready.cablecar
  • While a bit messy, this follows the convention of jbuilder,
    which makes it clear what renderer is being used