Home > Django, python > django – RuntimeWarning: DateTimeField received a naive datetime

django – RuntimeWarning: DateTimeField received a naive datetime

2 Febbraio 2017

Abbiamo un form

class ChangeForm(forms.Form):
    date = forms.DateField(label='date', initial=datetime.date.today)
    ...

e la view di competenza

def edit(request, item_id):
    myitem = get_object_or_404(AItem, pk=item_id)
    if request.method == "POST":
        form = ChangeForm(request.POST)
        if form.is_valid():
            myitem.date = form.cleaned_data['date']
            myitem.save()
            return redirect(...)
    else:
        form = ChangeForm(initial={'date': myitem.date})
    return render(request, 'atemplate.html',
                  {'form': form, 'myitem': myitem})

nel momento del salvataggio dei dati (POST) ottengo il warning in oggetto.

per risolvere il problema, tramite timezone di django, trasformiamo le date
da formato ‘naive’ a formato ‘aware’.
Nel mio caso la data è di tipo datetime.date per tento prima,
la trasformerò in formato datetime.datetime.

>>> import datetime
>>> from django.utils import timezone
>>> a_date = datetime.date.today()
>>> a_datetime = datetime.datetime.combine(a_date, datetime.time())
>>> a_datetime
datetime.datetime(2017, 2, 2, 0, 0)
>>> aware_date = timezone.make_aware(a_datetime, timezone.get_default_timezone())
>>> aware_date
datetime.datetime(2017, 2, 2, 0, 0, tzinfo=<UTC>)

oppure tramite il modulo pytz (installabile tramite pip):

>>> import pytz
>>> naive = datetime.datetime(2017, 2, 2, 12, 0, 0)
>>> aware = datetime.datetime(2017, 2, 2, 12, 0, 0, 0, pytz.UTC)
>>> aware == naive
Traceback (most recent call last):
  File "<console>", line 1, in <module>
TypeError: can't compare offset-naive and offset-aware datetimes
>>> aware == pytz.utc.localize(naive)
True

ora basta modificare la view con la gestione corretta delle date:

def edit(request, item_id):
    myitem = get_object_or_404(AItem, pk=item_id)
    if request.method == "POST":
        form = ChangeForm(request.POST)
        if form.is_valid():
            naive_date = form.cleaned_data['date']
            naive_datetime = datetime.datetime.combine(naive_date, datetime.time())
            myitem.date = timezone.make_aware(naive_datetime, 
                                              timezone.get_default_timezone())
            myitem.save()
            return redirect(...)
    else:
        form = ChangeForm(initial={'date': myitem.date})
    return render(request, 'atemplate.html',
                  {'form': form, 'myitem': myitem})
Categorie:Django, python Tag: ,
I commenti sono chiusi.