[PyGreSQL] DATETIME fields and DateTime objects in pgdb

[Christoph Zwerschke]

Hello Mario,

thanks for the feedback. We may consider some of this in version 3.9.

> pgdb returns DATETIME data as strings.  in the case switch for DATETIME
> pgdb does not make any attempt to convert it from the representing
> string into a DateTime object.  the result returned in fetch(one/all)
> does not hold any information about the original type in the database
> (indistinguishable from STRING).

I think the main problem here is that - as you already noticed - the 
date/time format can vary in PostGreSQL, depending on how you set 
datestyle. For instance, I have usually set datestyle=German, so your 
patch would not work. And datestyle can probably even altered during one 
session. I'm currently not sure how to get a universally valid solution.

Maybe somebody will come up with a good idea. One possibility would be 
to add a PyGreSQL configuration parameter that tells PyGreSQL if and how 
DateTimes should be treated, and it is in the responsibility of the 
application to set it appropriately.

Also, if we really want to return the type, then we should not only 
support absolute times, but also time delta types, and we should 
properly handle time zones and fractions of seconds in timestamps (your 
patch rounds all datetime types to seconds).

By the way, your patch changes a check for StringType to StringTypes 
(i.e. including unicode). I think this has been already changed in 
PyGreSQL since 3.6 or so. Unicode strings are automatically encoded to 
UTF-8 (actually, I think this is also not quite correct, since the 
server could have been configure with a different encoding).

You also write that the website is sometimes down and thus PyGreSQL not 
available. I did not experience this in the past, but a solution would 
be to put PyGreSQL in the cheese shop (PyPI) as well. D'Arcy, what do 
you think about that?

-- Christoph