Settings View Source Using application data

Sometimes we already have metrics that we want to display without going through the telemetry package. We want to expose the number of users created. The users table with the inserted_at is perfect for this. telemetry_ui provides a way use the existing metrics helpers with application-defined data:

count_over_time(:data,
  description: "Users count",
  unit: " users",
  data_resolver: fn options ->
    query =
      from(
        users in "users",
        select: %{date: users.inserted_at, count: 1},
        where: users.inserted_at >= ^options.from and users.inserted_at <= ^options.to
      )

    {:ok, MyApp.Repo.all(query)}
  end
)

The data_resolver options is specified here to return the data that will be displayed in the same graph layout as the telemetry_ui_events entries. The built-in metrics uses the same data_resolver options: data_resolver: &{:async, fn -> TelemetryUI.metric_data(&1, metric, &2) end}.