Lazy-load Rails partials via CableReady
π¨ BREAKING CHANGE: With v1.0, futurism has been transferred to the stimulusreflex organization. Please update your npm package to @stimulus_reflex/futurism
accordingly π¨
- Table of Contents
- Facts
- Usage
- API
- Events
- Installation
- Authentication
- Testing
- Gotchas
- Contributing
- License
- Contributors
- only one dependency: CableReady
- bundle size (without CableReady) is around ~2.46kB
- Chrome v67+ (v54+ via Polyfill)
- Firefox v63+
- Edge v79+
- Safari v10.1+ via Polyfill
- iOS Safari & Chrome v10.3+ via Polyfill
with a helper in your template
<%= futurize @posts, extends: :div do %>
<!-- placeholder -->
<% end %>
custom <futurism-element>
s (in the form of a <div>
or a <tr is="futurism-table-row">
are rendered. Those custom elements have an IntersectionObserver
attached that will send a signed global id to an ActionCable channel (FuturismChannel
) which will then replace the placeholders with the actual resource partial.
With that method, you could lazy load every class that has to_partial_path defined (ActiveModel has by default).
You can pass the placeholder as a block:
<%= futurize @posts, extends: :tr do %>
<td class="placeholder"></td>
<% end %>
You can also omit the placeholder, which falls back to eager loading.
Currently there are two ways to call futurize
, designed to wrap render
's behavior:
You can pass a single ActiveRecord
or an ActiveRecord::Relation
to futurize
, just as you would call render
:
<%= futurize @posts, extends: :tr do %>
<td class="placeholder"></td>
<% end %>
Remember that you can override the partial path in you models, like so:
class Post < ApplicationRecord
def to_partial_path
"home/post"
end
end
That way you get maximal flexibility when just specifying a single resource.
Call futurize
with a partial
keyword:
<%= futurize partial: "items/card", locals: {card: @card}, extends: :div do %>
<div class="spinner"></div>
<% end %>
You can also use the shorthand syntax:
<%= futurize "items/card", card: @card, extends: :div do %>
<div class="spinner"></div>
<% end %>
Collection rendering is also possible:
<%= futurize partial: "items/card", collection: @cards, extends: :div do %>
<div class="spinner"></div>
<% end %>
You can also pass in the controller that will be used to render the partial.
<%= futurize partial: "items/card", collection: @cards, controller: MyController, extends: :div do %>
<div class="spinner"></div>
<% end %>
By default (i.e. not passing in a value), futurize will use ApplicationController
, but you may override by setting the Futurism default controller in an initializer, for example config/initializers/futurism.rb
.
Futurism.default_controller = "MyController" # to avoid the controller from trying to autoload at boot, provide as a string
You can pass a hash of attribute/value pairs which will be mixed into the HTML markup for the placeholder element. This is important for layouts that require elements to have dimensionality. For example, many scripts calculate size based on element height and width. This option ensures that your elements have integrity, even if they are gone before you see them.
<%= futurize @posts, extends: :tr, html_options: {style: "width: 50px; height: 50px;"} do %>
<td class="placeholder"></td>
<% end %>
This will output the following:
<tr style="width: 50px; height: 50px;">
<td class="placeholder"></td>
</tr>
It may sound surprising to support eager loading in a lazy loading library π, but there's a quite simple use case:
Suppose you have some hidden interactive portion of your page, like a tab or dropdown. You don't want its content to block the initial page load, but once that is done, you occasionally don't want to wait for the element to become visible and trigger the IntersectionObserver
, you want to lazy load its contents right after it's added to the DOM.
Futurism makes that dead simple:
<%= futurize 'some_tab', eager: true, extends: :tr do %>
<div class="placeholder"</td>
<% end %>
In some rare cases, e.g. when combined with CableReady's async updates_for
mechanism, you'll want to bypass futurism entirely and fall back to native rendering
. You can do this by passing an unless
option:
<%= futurize 'some_tab', unless: bypass_futurism?, extends: :tr do %>
<div class="placeholder"</td>
<% end %>
Internally, this works the same as bypassing futurism in tests
Futurism's default behavior is to broadcast
partials as they are generated in batches:
On the client side, IntersectionObserver
events are triggered in a debounced fashion, so several render
s are performed on the server for each of those events. By default, futurism will group those to a single broadcast
call (to save server CPU time).
For collections, however, you can opt into individual broadcasts by specifying broadcast_each: true
in your helper usage:
<%= futurize @posts, broadcast_each: true, extends: :tr do %>
<div class="placeholder"</td>
<% end %>
For individual models or arbitrary collections, you can pass record
and index
to the placeholder block as arguments:
<%= futurize @post, extends: :div do |post| %>
<div><%= post.title %></div>
<% end %>
<%= futurize @posts, extends: :tr do |post, index| %>
<td><%= index + 1 %></td><td><%= post.title %></td>
<% end %>
<%= futurize partial: "users/user", collection: users, extends: "tr" do |user, index| %>
<td><%= index + 1 %></td><td><%= user.name %></td>
<% end >
Once your futurize element has been rendered, the futurism:appeared
custom event will be called.
Add this line to your application's Gemfile:
gem 'futurism'
And then execute:
$ bundle
To copy over the javascript files to your application, run
$ bin/rails futurism:install
! Note that the installer will run yarn add @stimulus_reflex/futurism
for you !
After bundle
, install the Javascript library:
There are a few ways to install the Futurism JavaScript client, depending on your application setup.
yarn add @stimulus_reflex/futurism
# config/importmap.rb
# ...
pin '@stimulus_reflex/futurism', to: 'futurism.min.js', preload: true
<!-- app/views/layouts/application.html.erb -->
<%= javascript_include_tag "futurism.umd.min.js", "data-turbo-track": "reload" %>
In your app/javascript/channels/index.js
, add the following
import * as Futurism from '@stimulus_reflex/futurism'
import consumer from './consumer'
Futurism.initializeElements()
Futurism.createSubscription(consumer)
For authentication, you can rely on ActionCable identifiers, for example, if you use Devise:
module ApplicationCable
class Connection < ActionCable::Connection::Base
identified_by :current_user
def connect
self.current_user = env["warden"].user || reject_unauthorized_connection
end
end
end
The Stimulus Reflex Docs have an excellent section about all sorts of authentication.
In Rails system tests there is a chance that flaky errors will occur due to Capybara not waiting for the placeholder elements to be replaced. To overcome this, add the flag
Futurism.skip_in_test = true
to an initializer, for example config/initializers/futurism.rb
.
Out of the box, Rails will prefix generated urls with http://example.org
rather than http://localhost
, much like ActionMailer. To amend this, add
# config/environments/development.rb
config.action_controller.default_url_options = {host: "localhost", port: 3000}
# config/environments/production.rb
config.action_controller.default_url_options = {host: "mysite.com"}
to your environments.
By default Futurism::CHannel will inherit from ApplicationCable::Channel, you can change this by setting
Futurism.configure do |config|
config.parent_channel = "CustomFuturismChannel"
end
in config/initializers.
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 futurism
cd futurism/javascript
yarn install # install all of the npm package's dependencies
yarn link # set the local machine's futurism npm package's lookup to this local path
# Setup a sample project, use the information below directly or use your own project
git clone https://github.com/leastbad/stimulus_reflex_harness.git
cd stimulus_reflex_harness
git checkout futurism
# Edit Gemfile to point point to local gem (e.g. `gem "futurism", path: "../futurism"`)
# yarn link @stimulus_reflex/futurism
# Do your work, Submit PR, Profit!
# To stop using your local version of futurism
# change your Gemfile back to the published (e.g. `gem "futurism"`)
cd path/to/futurism/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
- Make sure that you run
yarn
andbundle
to pick up the latest. - Bump version number at
lib/futurism/version.rb
. Pre-release versions use.preN
- Run
rake build
andyarn build
- Commit and push changes to github
git commit -m "Bump version to x.x.x"
- Run
rake release
- Run
yarn publish --no-git-tag-version
- Yarn will prompt you for the new version. Pre-release versions use
-preN
- Commit and push changes to GitHub
- 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.
Thanks goes to these wonderful people (emoji key):
This project follows the all-contributors specification. Contributions of any kind welcome!