# Scope broadcast to instance

**URL:** <https://discuss.hotwired.dev/t/scope-broadcast-to-instance/2973>\
**Category:** General\
**Created:** [June 17, 2021, 1:01am UTC](https://discuss.hotwired.dev/t/scope-broadcast-to-instance/2973 "2021-06-17T01:01:12Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![dpurp](https://yyz1.discourse-cdn.com/flex027/user_avatar/discuss.hotwired.dev/dpurp/32/762_2.png) [@dpurp](https://discuss.hotwired.dev/u/dpurp)\
**Post date:** [June 17, 2021, 1:01am UTC](https://discuss.hotwired.dev/t/scope-broadcast-to-instance/2973/1 "2021-06-17T01:01:12Z")

</div>

I’m having a hard time wrapping my head around how to broadcast via a model and where the Hotwire magic stops and where I have to step in. Apologies if this has been covered, but I can’t seem to find what must be a common use case. Throughout my app, I want to scope updates to a specific user – or in this case, to a specific client.

My case:

I have a Client model. A Client has\_many :hospitalizations.

I have two index views for hospitalizations.

One lists all hospitalizations:

```auto
views/hospitalizations/index.html.erb
views/hospitalizations/_hospitalization.html.erb

```

One is nested under clients:

```auto
views/clients/hospitalizations/index.html.erb
views/clients/hospitalizations/_hospitalizations.html.erb
views/clients/hospitalizations/_hospitalization.html.erb

```

I’d like to be able to update both the unscoped hospitalizations/index and the clients/hospitalizations/index.

So models/hospitalization.rb:

```auto
class Hospitalization < ApplicationRecord
  belongs_to :client
  belongs_to :staff

  after_create_commit do
    broadcast_prepend_to "hospitalizations",
                          partial: 'hospitalizations/hospitalization',
                          locals: { hospitalization: self },
                          target: 'hospitalizations'
    broadcast_prepend_to :client,
                          partial: 'clients/hospitalizations/hospitalization',
                          locals: { hospitalization: self },
                          target: 'client_hospitalizations'
...

```

I wasn’t sure whether I’m supposed to do something with client.rb, so:

```auto
class Client < ApplicationRecord

  broadcasts
  ...

```

And then, views/clients/hospitalizations/index.html.erb:

```auto
<%= turbo_stream_from :client %>
<%= render 'hospitalizations' %>

```

With the code I have now, when I create a new Hospitalization:

1. hospitalizations/hospitalization works great. The new row is prepended.
2. If I create a new hospitalization for client 4689, Hotwire will prepend the turbo-frame for all clients, not just 4689.

How do I scope the broadcast so that it only updates the client to whom the hospitalization belongs?

---

<div class="post-metadata">

**Author:** ![dpurp](https://yyz1.discourse-cdn.com/flex027/user_avatar/discuss.hotwired.dev/dpurp/32/762_2.png) [@dpurp](https://discuss.hotwired.dev/u/dpurp)\
**Post date:** [June 17, 2021, 1:20pm UTC](https://discuss.hotwired.dev/t/scope-broadcast-to-instance/2973/2 "2021-06-17T13:20:49Z")

</div>

OK, I think I have this working.

In model, for the `broadcast_prepend_to`, etc., helpers, I need to broadcast to the client instance, not a string or symbol. Also have to make sure I `broadcasts_to :client`.

```auto
# models/hospitalization.rb
class Hospitalization < ApplicationRecord
  belongs_to :client
  belongs_to :staff

  broadcasts_to :client

  after_create_commit -> (hospitalization) do
    broadcast_prepend_later_to "hospitalizations"
    broadcast_prepend_later_to hospitalization.client,
          partial: 'clients/hospitalizations/hospitalization',
          target: "client_#{hospitalization.client_id}_hospitalizations"
  end

  after_update_commit -> (hospitalization) do
    broadcast_replace_later_to "hospitalizations"
    broadcast_replace_later_to hospitalization.client,
          partial: 'clients/hospitalizations/hospitalization',
          target: "client_hospitalization_#{hospitalization.id}"
  end

  after_destroy_commit -> (hospitalization) do
    broadcast_remove_to "hospitalizations"
    broadcast_remove_to hospitalization.client,
          partial: 'clients/hospitalizations/hospitalization'
  end
...

```

Then, in client index, I need to stream from the client instance here, not a string or symbol:

```auto
# views/clients/hospitalizations/index.html.erb
<%= turbo_stream_from @client %>

```

Client collection partial needs a turbo frame ID that doesn’t match `hospitalizations`, which is already being used by `views/hospitalizations/index.html.erb`, so use unique ID like `client_4689_hospitalizations` as set above in target.

```auto
# views/clients/hospitalizations/_hospitalizations.html.erb
<%= turbo_frame_tag "client_#{@client.id}_hospitalizations" do %>
  <%= render @hospitalizations %>
<% end %>

```

Same for client instance partial. Prefix `client_` to turbo frame ID, so it doesn’t interfere with dom\_id of `views/hospitalizations/_hospitalization.html.erb`.

```auto
# views/clients/hospitalizations/_hospitalization.html.erb
<%= turbo_frame_tag "client_#{dom_id(hospitalization)}" do %>
<div class="span-eight tight">
    <h5><%= hospitalization.facility %></h5>
    <p><%= hospitalization.dates_to_s %></p>
    <%= simple_format hospitalization.comments %>  
</div>
<% end %>

```