can't compare offset-naive and offset-aware datetimes

[manelclos]

I tried to import a json file that was just exported.

settings.py contains USE_TZ=True

Line number: 1 - can't compare offset-naive and offset-aware datetimes
Traceback (most recent call last):
File "/apps/local/lib/python2.7/site-packages/import_export/resources.py", line 361, in import_data
if self.skip_row(instance, original):
File "/apps/local/lib/python2.7/site-packages/import_export/resources.py", line 266, in skip_row
if field.get_value(instance) != field.get_value(original):
TypeError: can't compare offset-naive and offset-aware datetimes

Same with CSV

[bmihelac]

@manelclos can you add failing tests?

[manelclos]

@bmihelac sure, will do. I'll look further into the issue too.

[manelclos]

Tests are ok for me. Also, I have latest code working on another installation. USE_TZ seems not to be the problem. It also works on PostgreSQL. It may have something to do with the previous, original values.

Field defined as:

models.DateTimeField(auto_now_add=True)

When exporting:

ORIGINAL:  2014-02-13 13:38:04.813096+00:00 <type 'datetime.datetime'>
EXPORT:  2014-02-13 13:38:04 <type 'str'>

When importing:

INSTANCE:  2014-02-13 13:38:04 <type 'datetime.datetime'>
ORIGINAL:  2014-02-13 13:38:04.813096+00:00 <type 'datetime.datetime'>

[manelclos]

Hi @bmihelac here is what I think we should do:

If the import works ok, just go ahead, this happens for me in different installations, and is also backwards compatible.

Then, if we get the TypeError exception, try to make the datetime timezone aware and compare again:

>>> value = '2014-02-13 10:37:38'
>>> format = "%Y-%m-%d %H:%M:%S"
>>> dt1 = datetime.strptime(value, format)
>>> dt1
datetime.datetime(2014, 2, 13, 10, 37, 38)
>>> from django.utils import timezone
>>> dt2 = timezone.make_aware(data, timezone.get_current_timezone())
>>> dt1.strftime(format)
'2014-02-13 10:37:38'
>>> dt2.strftime(format)
'2014-02-13 10:37:38'

https://docs.djangoproject.com/en/dev/topics/i18n/timezones/#troubleshooting

Then, I'll have only the microseconds problem, but that should be solved by adding a DateTime widget with the proper format, right?

[bmihelac]

@manelclos what do you think about checking USE_TZ setting instead of catching exception.

We would basically replace this line with:

dt = datetime.strptime(value, format)
if settings.USE_TZ:
    dt = timezone.make_aware(dt, timezone.get_default_timezone())
return dt

[manelclos]

@bmihelac Yes, makes more sense, though the impact is also bigger. I'll try the suggested change. Thanks!

[bmihelac]

Unfortunately strptime does not allow %z

[manelclos]

@bmihelac can you please review?