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Lightweight Resource-Based Presence Solution with CableReady



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Lightweight Resource-Based Presence Solution with CableReady.

Cubism provides real-time updates of who is viewing or interacting with whatever resources you need. Whether you want Slack's "X is typing..." indicator or an e-commerce "5 other customers are viewing this item" notice, Cubism gives you everything you need "under the hood" so that you can focus on what really matters—end-user functionality.

Table of Contents

  • Table of Contents
  • Usage
  • Installation
  • API
  • Limitations
  • Gotchas
  • Contributing
  • License
  • Contributors


Prepare your User Model

In your app's User model, include Cubism::User:

class User < ApplicationRecord
  include Cubism::User

  # ...

Track Present Users in your Models

In the models you'd like to track presence for, include the Cubism::Presence concern:

class Project < ApplicationRecord
  include Cubism::Presence

  # ...

Set Up the Cubicle Template

Using the cubicle_for helper, you can set up a presence indicator. It will

  1. subscribe to the respective resource, and
  2. render a block which is passed the list of present users:
<%= cubicle_for @project, current_user do |users| %>
  <%=", ")
<% end %>

Important! due to technical limitations the cubism block does not act as a closure, i.e. it has only access to the users variable passed to it - think of it more as a self-contained component.


Add this line to your application's Gemfile:

gem 'cubism'

And then execute:

$ bundle

There are a few ways to install the Cubism JavaScript client, depending on your application setup.

ESBuild / Webpacker

yarn add @minthesize/cubism

Import maps:

# config/importmap.rb
# ...
pin '@minthesize/cubism', to: 'cubism.min.js', preload: true

Rails Asset pipeline (Sprockets):

<!-- app/views/layouts/application.html.erb -->
<%= javascript_include_tag "cubism.umd.min.js", "data-turbo-track": "reload" %>


This gem uses kredis under the hood, so be sure to follow their installation instructions. In other words, provide a Redis instance and configure it in config/redis/shared.yml.


In your app's Javascript entrypoint (e.g. app/javascript/packs/application.js) import and initialize CableReady (cubism will make use of the injected ActionCable consumer):

import CableReady from "cable_ready";
import "@minthesize/cubism";

CableReady.initialize({ consumer });


The cubicle_for helper accepts the following options as keyword arguments:

  • scope: declare a scope in which presence indicators should appear. For example, if you want to divide between index and show views, do scope: :index and scope: :show respectively (default: "").
  • exclude_current_user (true|false): Whether or not to exclude the current user from the list of present users broadcasted to the view. Useful e.g. for "typing..." indicators (default: true).
  • appear_trigger: JavaScript event names (e.g. ["focus", "debounced:input]) to use. (Can also be a singular string, which will be converted to an array). The default is :connect, i.e. register a user as "appeared"/"present" when the element connects to the DOM. Another special value is :intersect, which fires when the trigger_root comes into the viewport.
  • disappear_trigger: a JavaScript event name (e.g. :blur) to use. (Can also be a singular string, which will be converted to an array). The default is :disconnect, i.e. remove a user form the present users list when the element disconnects from the DOM. Analoguous to above, :intersect means that disappear will fire when the trigger_root is scrolled out of the viewport.
  • trigger_root: a CSS selector to attach the appear/disappear events to. Defaults to the cubicle-element itself.
  • html_options are passed to the TagBuilder.


Supported Template Handlers

  • ERB


Usage with ViewComponent

Currently there's a bug in VC resulting in the capture helper not working correctly (github/view_component#974). The current workaround is to assign a slot in your component and render the presence list from outside:

class MyComponent < ViewComponent::Base
  renders_one :presence_list

  # ...
<%= render do |c| %>
  <% c.presence_list do %>
    <%= cubicle_for @project, current_user do |users| %>
    <% end %>
  <% end %>
<% end %>


Get local environment setup

Below are a set of instructions that may help you get a local development environment working

# Get the gem/npm package source locally
git clone
yarn install # install all of the npm package's dependencies
yarn link # set the local machine's cubism npm package's lookup to this local path

# Setup a sample project and edit Gemfile to point to local gem
# (e.g. `gem "cubism", path: "../cubism"`)
# yarn link @minthesize/cubism

# Do your work, Submit PR, Profit!

# To stop using your local version of cubism
# change your Gemfile back to the published (e.g. `gem "cubism"`)
cd path/to/cubism/javascript
# Stop using the local npm package
yarn unlink

# Instruct your project to reinstall the published version of the npm package
cd path/to/project
yarn install --force

📦 Releasing

  1. Make sure that you run yarn and bundle to pick up the latest.
  2. Bump version number at lib/cubism/version.rb. Pre-release versions use .preN
  3. Run rake build and yarn build
  4. Commit and push changes to github git commit -m "Bump version to x.x.x"
  5. Run rake release
  6. Run yarn publish --no-git-tag-version
  7. Yarn will prompt you for the new version. Pre-release versions use -preN
  8. Commit and push changes to GitHub
  9. Create a new release on GitHub (here) and generate the changelog for the stable release for it


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


Julian Rubisch