ViewComponent::Live

This is a small add-on to the ViewComponent gem to make your components update automatically when data is changed serverside.

Renamed to ViewComponent::Live to follow naming convention of ViewComponent gem

Usage

Lets say you have a MiniBasketComponent that is renders the small basket in the top of your webshop. Wouldn't it be nice if that just updated it self whenever a change happens to the draft order?

First lets create a small component for our mini basket. This component requires a DraftOrder and will listen to any change to the draft order it renders.

class MiniBasketComponent < ViewComponent::Base
  include ViewComponent::Live::Subscriber

  listen_to :draft_order

  def initialize(draft_order:)
    @order = draft_order
  end

  def count
    @order.product_count
  end

  def id
    @order.id
  end
end

Important! There is a strict naming requirement on the listen_to part and named argument in initialize!

Then the component view. Notice the = on the live block. It wraps the view in a div tag so we know what part of the page to update.

<%= live do %>
  <b><%= count %> products in basket</b>
<% end %>

Finally we need to tell our DraftOrder to broadcast changes.

class DraftOrder < ApplicationRecord
  include ViewComponent::Live::Broadcaster
end

Thats it. Now any update your draft order will be broadcast through ActionCable and your view will update in real time.

Installation

Add this line to your application's Gemfile:

gem 'view_component-live'

And then execute:

$ bundle

Add stimulus controller

$ yarn add stimulus-actionview-live, '1.0.0'

Add these 2 lines to your app/javascript/controllers/index.js

import LiveController from "stimulus-actionview-live"
application.register("live", LiveController)

Test

Running the tests requires a Redis server to have ActionCable running in a productionlike environment. This might seem like a bit overkill but this way one system test will test the entire gem.

In the test/dummy app there is a complete example of a live updating component. Note to self, remember to compile webpacker when making changes to dummy app assets

License

The gem is available as open source under the terms of the MIT License.

TODO

Nice to have

• install generator that does yarn add and adds lines to stimulus controllers file
• find a way to do collection updates, a component that lists many items
• could we do something for components that rely on multiple objects?
• allow the listen to method to accept a list of attributes so we only get updates to relevant things
• enable the live method to wrap component in any kind of tag