frenzy/lib/frenzy_web/controllers/fervor/paginator.ex

defmodule FrenzyWeb.Fervor.Paginator do
  import Ecto.Query

  def paginate(query, %{"max_id" => max_id}) do
    from(o in query, where: o.id < ^max_id, order_by: [desc: :id])
  end

  def paginate(query, %{"min_id" => min_id}) do
    from(o in query, where: o.id > ^min_id, order_by: [asc: :id])
  end

  def paginate(query, %{"since_id" => since_id}) do
    from(o in query, where: o.id > ^since_id, order_by: [desc: :id])
  end

  def paginate(query, _params) do
    from(query, order_by: [desc: :id])
  end

  def limit(query, params) do
    limit = Map.get(params, "limit", 20)
    from(query, limit: ^limit)
  end
end