The deserialization of DateTime fields doesn't match the documentation

According to the documentation for marshmallow.fields.DateTime:

Schema.load returns datetime objects that are timezone-aware.

But that doesn’t seem to be the case in 3.0.0b14:

>>> marshmallow.__version__
'3.0.0b14'
>>> d = marshmallow.fields.DateTime().deserialize('2018-09-18T16:53:11.876810+00:00')
>>> d
datetime.datetime(2018, 9, 18, 16, 53, 11)
>>> repr(d.tzinfo)
'None'

I would have expected the deserialized datetime’s tzinfo to be set. Or did I misunderstood the documentation?

[MattF-NSIDC]

Ran in to this issue today running unit tests in CircleCI which passed on my local machine. My schemas were loading timezone-aware strings to naive datetime objects, but the docs clearly say “Schema.load returns datetime objects that are timezone-aware.”

Installing python-dateutil fixed the problem. The code explicitly behaves differently depending on whether python-dateutil is installed on the system:

https://github.com/marshmallow-code/marshmallow/blob/fd3f2db051cd1cec6bce9cd18571efd18231a2aa/src/marshmallow/utils.py#L227

Can the docs please be updated to reflect this? That would have saved me some time today!

Or maybe marshmallow can be made dependent on python-dateutil? Would this help with platform independence?

[lafrech]

deckar01 I know it’s been a while but is it possible your 2.7 environment had python-dateutil installed, but it was not installed in 3.7?

I’m pretty sure that was the reason.

Further refactor will happen in #1234 but I believe the issue about lost timezone info is fixed already thanks to https://github.com/marshmallow-code/marshmallow/pull/1249, reworked in https://github.com/marshmallow-code/marshmallow/pull/1265.

The issue about the docs being inaccurate should be addressed during the refactor in #1234.