Methods

broadcast and broadcast_to immediately transmit all pending operations to subscribed ActionCable clients. Both methods can be called on an existing instance of CableReady::Channels or as the conclusion to a method chain.

cable_ready["MyIdentifier"] # CableReady::Channels instance, string identifier
cable_ready[UserChannel] # constant identifier, used to broadcast_to a resource

While data transmission is handled by ActionCable, the client-side channel subscriber must be configured to pass the received data to the CableReady client.

The default behavior of CableReady is to clear the operation queues for all streams immediately after delivering them. However, the developer can pass clear: false as the last keyword parameter to prevent clearing the queue. Not clearing the operations queue leaves it available for potential future broadcast methods to repeat.

String identifier

Constant identifier (for resources)

channel setup

stream_from "cookies"

stream_for Cookie.find(params[:id])

identifier

cable_ready["cookies"]

cable_ready[CookiesChannel]

send to client

broadcast

broadcast_to(cookie)

create job

broadcast_later

broadcast_later_to(cookie)

Using broadcast_later and broadcast_later_to are an excellent way to speed up Reflex actions, although creating jobs has its own overhead and the client could receive any operations performed by the job a few ms slower. After all, your users don't know what a Reflex is and likely don't care that it's finished if they are still waiting on content.

Perhaps the best reason to "go async" and let a job do all of the work is less about perceived speed and more about overall scalability. You don't want your Rails processes waiting for external IO, regardless of whether it's ActionDispatch or ActionCable doing the waiting.

If you are using Sidekiq, remember that jobs are guaranteed to run "at least once".

broadcast(*identifiers, clear: true)

This method operates on Channels which use the stream_from method in their subscribed method. broadcast is most frequently called with no arguments, which instructs CableReady to send one ActionCable payload for every string-based stream identifier with pending operations.

cable_ready.broadcast # deliver all pending operations with string identifiers

The developer is able to constrain the outcome by passing one (or several) identifiers to the method. Specifying identifiers empowers CableReady to temporarily ignore any queues associated with unspecified identifiers.

cable_ready["FirstIdentifier"].console_log(message: "gnarly!")
cable_ready["SecondIdentifier"].console_log(message: "rad!")
cable_ready["ThirdIdentifier"].console_log(message: "bodacious!")
cable_ready.broadcast("FirstIdentifier", "SecondIdentifier")
cable_ready.broadcast # sends third payload

Calling broadcast with no parameters delivers all queues identified by strings while ignoring any queues identified by constants.

If broadcast is called at the end of a method chain, there is no opportunity to change the identifier. In this context, broadcast only accepts the optional clear: false boolean argument.

broadcast_later(clear: true)

Batch up all of the outstanding operations, serialize them and send the result to an ActiveJob for processing. The job worker will take responsibility for actually broadcasting the operations.

This method can only be called at the end of a chain of operations, implying a single string-based stream identifier. It cannot be called in isolation to broadcast multiple channels the way broadcast can.

broadcast_later_to(model, clear: true)

When called at the end of an operation chain, broadcast_later_to will batch up all of the outstanding operations, serialize them and send the result to an ActiveJob for processing. The job worker will take responsibility for actually broadcasting the operations.

This method can only be called at the end of a chain of operations, implying a single resource as the stream identifier. It cannot be called in isolation to clear multiple channels the way broadcast_to can.

You must pass broadcast_to_later an ActiveRecord model so that the job knows what resource to broadcast the operations to.

broadcast_to(model, *identifiers, clear: true)

This method operates on Channels which use the stream_for method in their subscribed method. broadcast_to is most frequently called with its single mandatory argument, which is an instance of an ActiveRecord model. This instructs CableReady to send one ActionCable payload for every constant-based stream identifier with pending operations.

cable_ready[PostsChannel].morph(...)
cable_ready.broadcast_to(Post.find(1))
cable_ready[UserChannel].dispatch_event(...)
cable_ready.broadcast_to(current_user)

Similar to the broadcast method, the developer can deliver multiple constant-based identifiers, or constain the call to a subset. However, while we don't want to be prescriptive, the nature of the resource-driven functionality and the patterns it enables means that most applications using constant-based identifiers will likely be used in a 1:1 channel-to-broadcast capacity. It's actually difficult to come up with a realistic example:

cable_ready[PostsChannel].dispatch_event(...)
cable_ready[CommentsChannel].dispatch_event(...)
cable_ready[VotesChannel].inner_html(...)
cable_ready.broadcast_to(Post.find(1), PostsChannel, CommentsChannel)
cable_ready.broadcast_to(Comment.find(1)) # sends to VotesChannel

Calling broadcast_to with only an ActiveRecord model parameter delivers all queues identified by constants while ignoring any queues identified by strings.

If broadcast_to is called at the end of a method chain, there is no opportunity to change the identifier. In this context, broadcast_to accepts only model and the optional clear: false boolean argument.

dom_id(record, prefix = nil)

Every class which includes CableReady::Broadcaster has access to a special, server-side version of the Rails dom_id helper. Whereas the view helper is typically used to generate id values for rendering DOM elements which map cleanly to ActiveRecord model instances, this method is intended to generate CSS selector strings used by CableReady to locate those DOM elements.

This method is a superset of the functionality offered by the native Rails version. It is otherwise functionally identical to the view template version except that it prefixes the generated string with # so that it can be passed directly to document.querySelector() on the client. This syntactic sugar means you can use a clever DSL instead of ugly string concatenations.

In addition to accepting model instances, CableReady's dom_id can also accept ActiveRecord::Relation objects, which are are pluralized. Finally, it will also accept any object which can be turned into a String, such as a constantized class name.

This method is automatically available in all StimulusReflex Reflex classes. This means that you can deploy some extremely sexy morph Reflexes:

class PostsReflex < ApplicationReflex
def latest
post = Post.last
# no need to write ugly "#post_#{post.id}"
morph dom_id(post), render(post)
dom_id(User.all) # "#users"
dom_id(User.all, :happy) # "#happy_users"
dom_id(User, :angry) # "#angry_user"
end
end