[storm] Like on DateTime using only date

[James Henstridge]

On 04/03/2008, Lutz Horn <lutz.horn at fastmail.fm> wrote:
> Hi Gustavo,
>
>  Am 03.03.2008 um 17:21 schrieb Gustavo Niemeyer:
>
> >> with at DateTime property I'd like to compare only using the date
>  >> part. But the like method of DateTime needs a datetime.datetime
>  >> instance, not a datetime.date instance. How can I formulate the like
>  >> condition to only select those records whose DateTime propery match a
>  >> datetime.date instance?
>  >
>  > I'm not sure I understand what's the problem you're facing.  The
>  > DateTime indeed needs a datatime object.  We may extend it to support
>  > automatic conversion from date objects, but it should be fairly simple
>  > to make it work as it is now.
>  >
>  > Can you provide some sample code that is failing, and that you're
>  > having
>  > trouble to make it work correctly?
>
>
>
> I've the following table in MySQL:
>
>  mysql> describe screenings;
>  +----------+--------------+------+-----+---------+----------------+
>  | Field    | Type         | Null | Key | Default | Extra          |
>  +----------+--------------+------+-----+---------+----------------+
>  | id       | int(11)      |      | PRI | NULL    | auto_increment |
>  | when     | datetime     | YES  |     | NULL    |                |
>  | movie_id | int(11)      | YES  |     | NULL    |                |
>  +----------+--------------+------+-----+---------+----------------+
>
>  Using Strom, the corresponding model class is:
>
>  class Screening(object):
>      __storm_table__ = "screenings"
>      id = Int(primary=True)
>      when = DateTime()
>
>  Now I want to find all screenings for today:
>
>  s_today = [screening for screening in
>             self.store.find(Screening,
>  Screening.when.like(datetime.datetime.now()))]
>
>  This obviously returns an empty list since to no screening happens
>  exactly now. But if I use datetime.date.today() as the parameter for
>  like(), I get
>
>  <type 'exceptions.TypeError'> at /
>  Expected datetime, found datetime.date(2008, 3, 3)
>
>  How can I use find() to get all Screening instances for which the date
>  part for the DateTime property equals datetime.date.today() regardless
>  of the time part?

You could try something like this:

today = datetime.date.today()
start = datetime.datetime.combine(today, datetime.time(0,0))
end = start + datetime.timedelta(days=1)

results = self.store.find(
    Screening, Screening.when >= start, Screening.when < end)

That is, pick all screenings that fall within the desired time interval.

James.