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Live comments with model broadcasts + turbo_stream_from

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                  class Comment < ApplicationRecord
  belongs_to :post
  belongs_to :author, class_name: 'Member'

  after_create_commit -> { broadcast_prepend_later_to(post, target: dom_id(post, :comments)) }
end

                  <%= turbo_stream_from @post %>

<div id="<%= dom_id(@post, :comments) %>">
  <%= render @post.comments.includes(:author).order(created_at: :desc) %>
</div>

                  <div id="<%= dom_id(comment) %>" class="border-b py-3">
  <div class="text-sm text-gray-600"><%= comment.author.nickname %></div>
  <div class="mt-1"><%= simple_format(comment.body) %></div>
</div>

If a feature is fundamentally “live” (comments, activity), I reach for model broadcasts. Rails can broadcast Turbo Stream fragments on after_create_commit, and the UI subscribes with turbo_stream_from. The beauty is that it’s still server-rendered HTML: I broadcast a partial, not JSON. I scope streams carefully (usually per parent record) so you don’t leak updates across pages. This is a huge productivity win because you get realtime updates without building a bespoke ActionCable protocol. The downside is you need to be intentional about N+1 in your partials and about authorization: only subscribe users who should see the stream.

Henry Kim

More from Henry Kim

Live comments with model broadcasts + turbo_stream_from

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More from Henry Kim