Behaviour for domain events stored in the event log.

use Counterpoint.Event injects:

• A default type_string/0 that returns the last segment of the module name (e.g. MyApp.Events.OrderPlaced → "OrderPlaced").
• A default tags/1 that returns [].

Both defaults can be overridden.

Example

defmodule MyApp.Events.OrderPlaced do
  use Counterpoint.Event

  defstruct [:order_id, :total]

  # override tags to enable tag-based filtering
  def tags(%__MODULE__{order_id: id}), do: ["order_id:#{id}"]

  def to_map(%__MODULE__{order_id: id, total: t}),
    do: %{"order_id" => id, "total" => t}

  def from_map(%{"order_id" => id, "total" => t}),
    do: %__MODULE__{order_id: id, total: t}
end

Remember to register the module in the events: list passed to Counterpoint.Supervisor so it can be deserialized from the store.