# `Honeybadger.EventFilter.Mixin`
[🔗](https://github.com/honeybadger-io/honeybadger-elixir/blob/v0.30.2/lib/honeybadger/event_filter/mixin.ex#L1)

Provides a mixin for implementing the Honeybadger.EventFilter behaviour.

If you need to implement custom filtering for events, you can define your own filter module
and register it in the config. For example, to filter based on event_type:

    defmodule MyApp.MyFilter do
      use Honeybadger.EventFilter.Mixin

      # Drop analytics events by returning nil
      def filter_event(%{event_type: "analytics"} = _event), do: nil

      # Anonymize user data in login events
      def filter_event(%{event_type: "login"} = event) do
        event
        |> update_in([:data, :user_email], fn _ -> "[REDACTED]" end)
        |> put_in([:metadata, :filtered], true)
      end

      # For telemetry events, you can customize while still applying default filtering
      def filter_telemetry_event(data, raw, event) do
        # First apply default filtering
        filtered_data = apply_default_telemetry_filtering(data)

        # Then apply custom logic
        case event do
          [:auth, :login, :start] ->
            Map.put(filtered_data, :security_filtered, true)
          _ ->
            filtered_data
        end
      end

      # Keep all other events as they are
      def filter_event(event), do: event
    end

And set the configuration to:

    config :honeybadger,
      event_filter: MyApp.MyFilter

Return `nil` from `filter_event/1` to prevent the event from being processed.
If you override `filter_telemetry_event/3`, you can still apply the default
filtering by calling `apply_default_telemetry_filtering/1`.

---

*Consult [api-reference.md](api-reference.md) for complete listing*