Add CURRENT_TIMESTAMP function to db.functions

[Curtis Maloney]

00:21 <+jarshwah> or.. Func(template='NOW()', output_field=DateTimeFIeld()) would work too

Postgres, MySQL, SQLite and MS SQL support this function, and it would be very handy.

In the past I've implemented it using an ExpressionNode, but with the new functions module, it could be simpler and more useful.

[Josh Smeaton]

Below is probably the way to go. We haven't done 0-arity Func expressions before though, so there may be some hidden traps waiting. It'd go in django.db.models.functions.py

class Now(Func):
    template = 'CURRENT_TIMESTAMP()'
    def __init__(self, output_field=DateTimeField(), **extra):
        super(Func, self).__init__(output_field=output_field, **extra)

This should (famous last words) be a relatively straight forward patch. I'd encourage someone that wants to get some basic familiarity with the ORM and expressions in general to have a go at implementing.

[Adam Johnson]

Pull request: ​https://github.com/django/django/pull/4722

[Tim Graham <timograham@…>]

In 23048d18:

Fixed #24866 -- Added Now() database function