BrightEyesDavid
I have a UTC datetime from a timestamptz PostgreSQL column, and am trying to:
- convert it to the user’s timezone;
- output a localised string representation for the frontend.
I’m trying to use DateTime for 1 and Cldr.DateTime for 2.
iex> {:ok, shifted} = DateTime.shift_zone(~U[2024-07-13 21:33:23.163097Z], "Europe/Berlin")
{:ok, #DateTime<2024-07-13 23:33:23.163097+02:00 CEST Europe/Berlin>}
However, Cldr.DateTime.to_string/2 doesn’t accept #DateTime<...>:
iex> {:ok, result} = Cldr.DateTime.to_string(shifted, "en-GB")
** (MatchError) no match of right hand side value: {:error, {ArgumentError, "Invalid DateTime. DateTime is a map that contains at least :year, :month, :day, :hour, :minute, :second and :calendar. Found: #DateTime<2024-07-13 23:33:23.163097+02:00 CEST Europe/Berlin Cldr.Calendar.Gregorian>"}}
(stdlib 4.3.1.3) erl_eval.erl:496: :erl_eval.expr/6
iex:3: (file)
I don’t know what #...<...> means, exactly, or how to convert it to a DateTime struct/map that Cldr.DateTime can use. Thanks.
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belaustegui
Looks like you are calling Cldr.DateTime.to_string incorrectly.
The locale must be passed as a keyword list. This should work:
BrightEyesDavid
So the
#...<...>syntax is an alternative representation of a struct? I tried searching for information on that, but I must have done that wrong, too.dimitarvp
It’s simply human-friendly formatting, suitable for quickly taking a look.
LostKobrakai
See Inspect — Elixir v1.12.3
kip
I’ve published ex_cldr_dates_times version 2.20.2 that improves the error message when options are not provided as a keyword list. Using your example:
BrightEyesDavid
@dimitarvp, @LostKobrakai, thanks. So the use of # seems to be related to a comment marker, as the representation is not valid Elixir syntax. In 1.17’s documentation: Inspect — Elixir v1.17.2. That mentions that
#Name<...>tends to be used when there are private fields to hide. I guess in the case of DateTime it’s used for conciseness.@kip, thanks, and thanks very much for your libraries!