librelist archives

Re: [flask] jinja question about timezone

From:

Andreas Christoffersen

Date:

2012-07-31 @ 05:29

Hi Audrius,

this is what I have:

dktid = pytz.timezone("Europe/Copenhagen")

# database configuration

MONGODB_HOST = 'localhost'
MONGODB_PORT = 27017


# Flask start

app = Flask(__name__)
app.config.from_object(__name__)


# connect to the database

# tz_aware = true cf.

http://api.mongodb.org/python/2.0/faq.html#what-is-the-correct-way-to-handle-time-zones-with-pymongo
connection = Connection(app.config['MONGODB_HOST'],
                    app.config['MONGODB_PORT'], tz_aware= True)



This works (stamp_time is returned directly in the jinja template {{
stamp_time }} not through mongo)

now = datetime.utcnow()
now = now.replace(tzinfo=pytz.utc)
stamp_time = now.astimezone(dktid).strftime('%d. %B %Y, kl. %H:%M'),


So my problem is how to handle this when iterating over the mongodb object
in the jinja template.

While this works:

{{ i['time'].strftime('%d. %B %Y, kl. %H:%M') }}


This doesn't:

{{ i['time'].astimezone(dktid).strftime('%d. %B %Y, kl. %H:%M') }}


I hope this clears it up.



>
> What is the timezone of datetime objects returned by MongoDB?  They
> should either be in UTC or naive objects without any timezone at all.
>
> According to pytz docs, the preferred way is to use UTC timezone
> internally and convert to localtime only when generating output meant
> for humans.
>
>   >>> localtime = pytz.timezone('Europe/Copenhagen')
>   >>> datetime.utcnow().replace(tzinfo=pytz.utc).astimezone(localtime)
>
> or
>
>   >>> datetime(2012, 1, 1, tzinfo=pytz.utc).astimezone(localtime)
>
> --
> Audrius Kažukauskas
> http://neutrino.lt/
>

On Tue, 2012-07-31 at 07:29:04 +0200, Andreas Christoffersen wrote:
> # tz_aware = true cf.
> 
http://api.mongodb.org/python/2.0/faq.html#what-is-the-correct-way-to-handle-time-zones-with-pymongo
> connection = Connection(app.config['MONGODB_HOST'],
>                     app.config['MONGODB_PORT'], tz_aware= True)

If I understood it correctly, this configuration is OK (returned
datetime objects use UTC timezone).

> This works (stamp_time is returned directly in the jinja template {{
> stamp_time }} not through mongo)
> 
> now = datetime.utcnow()
> now = now.replace(tzinfo=pytz.utc)
> stamp_time = now.astimezone(dktid).strftime('%d. %B %Y, kl. %H:%M'),
> 
> 
> So my problem is how to handle this when iterating over the mongodb object
> in the jinja template.
> 
> While this works:
> 
> {{ i['time'].strftime('%d. %B %Y, kl. %H:%M') }}
> 
> This doesn't:
> 
> {{ i['time'].astimezone(dktid).strftime('%d. %B %Y, kl. %H:%M') }}

When you say it doesn't work, what exactly is happening?  Do you get an
error?

-- 
Audrius Kažukauskas
http://neutrino.lt/

Just ran the code to reproduce the error message. Amazing - it seems to
works now! - sorry for the trouble caused. I am embarrased. Don't know what
I did wrong the last time.


> When you say it doesn't work, what exactly is happening?  Do you get an
> error?
>
> --
> Audrius Kažukauskas
> http://neutrino.lt/
>