Empty time values should be stored as NULL

[Ryan J Ollos]

Empty time values in the ticket system are stored as 0. They should probably be stored as NULL instead. Example: Version.update​

sqlite> SELECT time FROM version;
0
1496041616000000
1472327798000000
0
0

The issue is caused by behavior of to_utimestamp​. We should add a helper function:

def _to_timestamp(time):
    return to_utimestamp(time) if time else None

Timestamps are stored in the following fields:

• attachment.time
• wiki.time
• revision.time
• ticket.time
• ticket.changetime
• ticket_change.time
• milestone.due
• milestone.completed
• version.time
• notification_subscription.time
• notification_subscription.changetime

[Ryan J Ollos]

See also comment:20:ticket:11018. Empty time ticket custom field values are stored as NULL rather than an empty string.

[Ryan J Ollos]

Milestone renamed