I think this is almost done now. select queries work fine. But surprisingly object queries override response_handler from select, so aren't currently working. It's just a matter of shuffling some logic around.

Update: objects queries now work too.

Now we need to work out what to do with SQLite - I might just raise a ValueError for now.

Update: I was able to get SQLite working.

@dantownsend I tried your solution and everything worked great. Here is a Piccolo shell results

# if we declare a time zone in the table definition
# class TallinnConcerts(Table):
# event_start = Timestamptz(at_time_zone=ZoneInfo("Europe/Tallinn"))
In [1]: await TallinnConcerts.select()
Out[1]: 
[{'id': 1,
 'event_start': datetime.datetime(2024, 4, 5, 10, 44, 46, tzinfo=zoneinfo.ZoneInfo(key='Europe/Tallinn'))},
 {'id': 2,
 'event_start': datetime.datetime(2024, 4, 5, 10, 44, 46, tzinfo=zoneinfo.ZoneInfo(key='Europe/Tallinn'))}]
In [2]: [i.to_dict() for i in await TallinnConcerts.objects()]
Out[2]: 
[{'id': 1,
 'event_start': datetime.datetime(2024, 4, 5, 10, 44, 46, tzinfo=zoneinfo.ZoneInfo(key='Europe/Tallinn'))},
 {'id': 2,
 'event_start': datetime.datetime(2024, 4, 5, 10, 44, 46, tzinfo=zoneinfo.ZoneInfo(key='Europe/Tallinn'))}]
# if we do not declare a timezone in the table definition, we can define `at_time_zone` in the select query
# class TallinnConcerts(Table):
# event_start = Timestamptz()
In [3]: await TallinnConcerts.select(TallinnConcerts.event_start.at_time_zone("Europe/Tallinn"))
Out[3]: 
[{'event_start': datetime.datetime(2024, 4, 6, 16, 37, 33, tzinfo=zoneinfo.ZoneInfo(key='Europe/Tallinn'))},
 {'event_start': datetime.datetime(2024, 4, 6, 16, 37, 33, tzinfo=zoneinfo.ZoneInfo(key='Europe/Tallinn'))}]

Piccolo Admin also work.

@sinisaos Thanks a lot for testing it.

What do you think about the design of it?

I changed it to be:

Timestamptz(at_time_zone=ZoneInfo("America/New_York"))

So the argument is at_time_zone, instead of tz to be consistent with the at_time_zone method name, and to make it clearer what it does.

I was thinking of adding a method to the objects query too. For select we can do this:

await Concert.select(Concert.starts_at.at_time_zone('America/Los_Angeles'))

But there's currently no way of overriding it for objects queries. Maybe something like:

await Concert.objects().at_time_zone({Concert.starts_at: 'America/Los_Angeles'})

@dantownsend Everything looks and works great to me, as I wrote in the previous comment.

But there's currently no way of overriding it for objects queries. Maybe something like:

await Concert.objects().at_time_zone({Concert.starts_at: 'America/Los_Angeles'})

It would be great to have that objects method to manipulate the results.

@sinisaos Thanks a lot for testing it.

What do you think about the design of it?

I changed it to be:

Timestamptz(at_time_zone=ZoneInfo("America/New_York"))

So the argument is at_time_zone, instead of tz to be consistent with the at_time_zone method name, and to make it clearer what it does.

I was thinking of adding a method to the objects query too. For select we can do this:

await Concert.select(Concert.starts_at.at_time_zone('America/Los_Angeles'))

But there's currently no way of overriding it for objects queries. Maybe something like:

await Concert.objects().at_time_zone({Concert.starts_at: 'America/Los_Angeles'})

I quite like this polars-like select expression (or should I say polars is piccolo-like 😊?), which feels natural to use. Additionally, I agree with @sinisaos that the syntax of the objects method looks good to me.