No longer able to convert Ecto.DateTime.to_erl

My goal is to find time difference in minutes:

 {_, {_, aaa, _}} = Ecto.DateTime.to_erl(d1) |> :calendar.time_difference(:calendar.universal_time)

I have a timestamp retrieved from Postgresql:

iex(13)> d1
~N[2017-02-09 07:23:04.000000]

Previously this worked well:

d11 = Ecto.DateTime.to_erl(d1)

But now it throws an exception:

* (FunctionClauseError) no function clause matching in Ecto.DateTime.to_erl/1
    (ecto) lib/ecto/date_time.ex:608: Ecto.DateTime.to_erl(~N[2017-02-09 07:23:04.000000])

How to fix that?

I'm not willing to use external libraries such as times.

Solution

For some reason, the DateTime value you have in RDBMS lacks the timezone information. There is a main difference between Ecto.DateTime and NaiveDateTime: the former cares about timezones, and the latter does not (as well as standard erlang datetime.)

iex(1)> d1 = ~N[2017-02-09 07:23:04.000000]
~N[2017-02-09 07:23:04.000000]
iex(2)> NaiveDateTime.to_erl d1
{{2017, 2, 9}, {7, 23, 4}}

From the snippet above one might see, that the conversion is still possible with NaiveDateTime.to_erl/1.

The core solution would be to find the cause of having naïve datetime value in the RDBMS and fix it.