DateTime fields lose resolution when serialized

[Gorka Eguileor]

Cinderlib's methods and property that convert objects to json end up losing resolution on DateTime fields.

Since json doesn't have a datetime fields they are stored as strings, but they are not storing subsecond information.

This means that datetime fields that are serialized and then deserialized are different.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/cinderlib/+/798633

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/cinderlib/+/798633
Committed: https://opendev.org/openstack/cinderlib/commit/51609b61a43d53119c8e8e00ae5ef5e919e85a27
Submitter: "Zuul (22348)"
Branch: master

commit 51609b61a43d53119c8e8e00ae5ef5e919e85a27
Author: Gorka Eguileor <email address hidden>
Date: Tue Jun 29 11:56:54 2021 +0200

    Fix datetime serialization

    Cinderlib's methods and property that convert objects to json end up
    losing resolution on DateTime fields.

    Since json doesn't have a datetime fields they are stored as strings,
    but they are not storing subsecond information.

    This means that datetime fields that are serialized and then
    deserialized are different.

    This patch changes the way we format the string to use the ISO-8601
    subsecond format instead of the standard second format.

    This is a backward compatible change, as this version of cinderlib will
    be able to read old datetime string, and old cinderlib code will be able
    to read new datetime strings as well (even if it cannot generate them).

    The old code is able to read the new format because the from_primitive
    code of the OVO field uses oslo_utils.timeutils.parse_isotime which in
    the end uses iso8601.parse_date, and since the subsecond format is also
    ISO8601 it is properly parsed.

    Change-Id: I1422e833ec0ec50376d4afac91f22c7b60bf996b
    Closes-Bug: #1933964

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/cinderlib 4.0.0 release.