Default time values in Yesod with PostgreSQL about yesodweb.com-content

[snoyberg]

I just tried using now() as the default value, and it appeared to work correctly:

postgres=# create table tmp(x INTEGER,foo timestamp with time zone default now());
CREATE TABLE
postgres=# insert into tmp(x) values(0);
INSERT 0 1
postgres=# select * from tmp;
 x |              foo              
---+-------------------------------
 0 | 2014-07-31 14:05:58.407412+03
(1 row)

And in fact, I ran the command at 14:05 in my current time zone (UTC+3). Can you clarify how you determined the now() was not a sufficient default?

[bholst]

Well, it works correctly and does what you expect when having a column with time zone. However, yesod (or persistent) creates a column without time zone for the type UTCTime.

test=# create table tmp(x INTEGER,foo timestamp without time zone default now());
CREATE TABLE
test=# insert into tmp(x) values(0);
INSERT 0 1
test=# select * from tmp;
 x |            foo             
---+----------------------------
 0 | 2014-07-31 15:07:31.461828
(1 row)

I ran this command at 15:07 in my current time zone (UTC+2). So this is not the UTC time in the table.
With now() at time zone 'utc' everything works as expected and I get

test=# select * from tmp;
 x |            foo             
---+----------------------------
 0 | 2014-07-31 13:07:31.461828
(1 row)

In contrast to that, a time from getCurrentTime in Haskell is always printed as UTC and persistent insert this into the database like that. Again, if you use a table with without timestamp as the default configuration does, it inserts the UTC time with dropping the time zone.

> getCurrentTime >>= print
2014-07-31 13:12:58.708879 UTC

[snoyberg]

Ahh, right, I forgot about that. We're about to release persistent 2.0, which will fix this bug. In the meanwhile, you can use ZonedTime instead of UTCTime.

[bholst]

Thanks!
Just to make sure I understood you correctly:
persistent 2.0 will use timestamp with time zone by default?

[snoyberg]

Yes.