Hey everyone!

In my app I have this resource (some parts omitted):

defmodule MyApp.Vote do
  use Ash.Resource,
    data_layer: AshPostgres.DataLayer

  actions do
    create :cast do
      argument :poll_id, :uuid, allow_nil?: false
      argument :option_id, :uuid, allow_nil?: false

      upsert? true
      upsert_identity :unique_voter_per_poll

      change manage_relationship(:poll_id, :poll, type: :append_and_remove)
      change manage_relationship(:option_id, :option, type: :append_and_remove)
      change relate_actor(:voter)
    end
  end

  relationships do
    belongs_to :poll, Poll do
      primary_key? true
      allow_nil? false
    end

    belongs_to :option, Option do
      primary_key? true
      allow_nil? false
    end

    belongs_to :voter, Voter do
      primary_key? true
      allow_nil? false
    end
  end

  identities do
    identity :unique_voter_per_poll, [:voter_id, :poll_id]
  end

  code_interface do
    define_for MyApp.Voting
    define :cast, args: [:poll_id, :option_id]
  end
end

If a voter casts their vote for another option in the same poll, this is an upsert so the new option id overwrites the old one.

Now, I want to publish updates on a pubsub because I want to display (and update) the count of votes for each option in a Live View. This means that when I cast a vote, I want to receive a vote event for the option_id, but I also want to receive an unvote event for the previous option_id.

What is the recommended way to do this?