Allow broadcasting without rendering and broadcasting with custom attributes

[davidalejandroaguilar]

Description

Key Enhancements

This PR improves the flexibility of custom Turbo Stream actions by allowing:

• Broadcasting without rendering
  • Some custom actions don't need any rendering at all because they're custom actions.
• Enabling passing custom attributes via the Broadcastable concern.
  • These custom actions might need them.

Motivation

Thanks to the work on hotwired/turbo#479 and #373, custom turbo_stream actions can now be created. However, some limitations still exist (See here for an example of both current limitations):

• Limited flexibility for passing extra attributes
  • Currently, extra attributes can only be passed via turbo_stream_action_tag and turbo_stream.
• Inability to use custom actions via models (which use the Broadcastable concern)
  • Broadcasting custom actions to any streamable/model is not possible. It can only be done via a turbo_stream response on the controller or inside a view response (.turbo_stream.erb) for a single user.

Example

A custom stream action that doesn't need a template, only attributes (e.g. a toast):

StreamActions.toast = function () {
  const text = this.getAttribute('text');
  const duration = Number(this.getAttribute('duration') || 3000);

  const toast = Toastify({
    text,
    duration,
  });

  toast.showToast();
};

Create a module with custom broadcast methods, just to encapsulate them and include them wherever we want:

module TurboBroadcastable
  def toast(text, duration: 3000)
    broadcast_action_later(
      :toast,
      render: false, # New in this PR
      attributes: {  # New in this PR
        text: 
        duration:
      }
    )
  end
end

Including it on ApplicationRecord so that we can toast to any model/streamable (as long as they're listening through turbo_stream_from.

class ApplicationRecord < ActiveRecord::Base
  include TurboBroadcastable
end

To be called anywhere, such as from a controller:

class WebhooksController < ApplicationController
  def create
    # ...
    Current.user.toast("Webhook received")
  end
end

Notes

This change only affects broadcast_action_ and related action_ methods, since this is the method you'd use for custom actions.

The default Javascript implementations for actions such as prepend, append, etc. are provided by Turbo on StreamAction and thus passing attributes here is unnecessary, since they won't be used.

[davidalejandroaguilar]

@seanpdoyle @dhh Hey there, it's been 4 months since I opened this PR. I know y'all are super busy, but I wonder if you could skim through this PR. It's a really simple change that creates a lot of flexibility and power. Basically it's allowing:

• Passing attributes to action broadcasts methods.
• Passing render: false to broadcast methods to avoid rendering any HTML and just sending the broadcast over the wire.

I'm unfamiliar with the repo's rules or usual wait times, so I'm unsure if this PR has been silently rejected or not. Appreciate your time and efforts spent bringing this project to life.

[dhh]

I'm fine with the changes, but the test suite need to pass. Can you have a look at that?

[davidalejandroaguilar]

@dhh Done, tests are passing now! Thank you.

[davidalejandroaguilar]

@dhh I think I missed you by a week 🤦🏼‍♂️ , so just a friendly ping on this after 2 weeks.

Wouldn't like to pester with notifications though, so LMK if I just need to be patient.

[davidalejandroaguilar]

I'm fine with the changes, but the test suite need to pass. Can you have a look at that?

@dhh Another friendly ping, test are passing 😃

[dhh]

Need to settle the commented out tests. Can't merge with that is it is.

[davidalejandroaguilar]

@dhh All good now!

(Had to call @message.save! first on the broadcast later tests, the discard_on config on the job was silently failing) 🤦🏼‍♂️

[davidalejandroaguilar]

@dhh Another month has passed, so I'm feeling free to ping you on this 😃

All tests are passing and ready to merge!

[davidalejandroaguilar]

@dhh Pinging you on this again, hoping y'all are out of a cycle and have time to merge? 😃

P.S. I'm pinging on a ~3-4 weeks interval so as to not annoy you. Let me know if this is too frequent.

[davidalejandroaguilar]

@dhh Pinging once more 😶

Another cool usage thanks to this PR that I just added to my app. Printing from anywhere:

# From anywhere
Current.venue.print(data)

Thanks to:

module TurboBroadcastable
  def print(data:, to: self)
    broadcast_action_later_to(
      to,
      action: :print,
      render: false, # New in this PR
      attributes: {  # New in this PR
        data: data.to_json
      }
    )
  end
end

class ApplicationRecord < ActiveRecord::Base
  include TurboBroadcastable
end

StreamActions.print = async function () {
  const printerService = new PrinterService();
  await printerService.print(this.getAttribute("data"));
}