on_conflict.ex

defmodule Upa.VideoWatchProgress do
  def save(attrs) do
    struct(Upa.VideoWatchProgress, attrs)
    |> changeset
    |> Upa.Repo.insert(on_conflict: insert_conflict_strategy(attrs))
    |> case do
      {:error, _} = error -> raise Upa.DatabaseCommandError
      {:ok, changeset} -> :ok
    end
  end

  def insert_conflict_strategy(%{fully_watched: fully_watched}) do
    from(v in Upa.VideoWatchProgress,
      update: [set: [
          milliseconds_watched: fragment("IF(last_event_timestamp < VALUES(last_event_timestamp), VALUES(milliseconds_watched), milliseconds_watched)"),
          last_event_timestamp: fragment("IF(last_event_timestamp < VALUES(last_event_timestamp), VALUES(last_event_timestamp), last_event_timestamp)"),
          updated_at: ^ecto_time(),
          fully_watched: ^fully_watched
        ]
      ]
    )
  end
end