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relationalai.std.dates.date.fromdatetime()

date.fromdatetime(datetime: datetime|Producer, tz: tzinfo|str|Producer = "UTC") -> Expression

Constructs a date value from a datetime value by discarding the time components. If tz is specified, the datetime is converted to the specified timezone or offset string before extracting the date. Must be called in a rule or query context.

Parameters

Name	Type	Description
`datetime`	`Producer` or Python `datetime` object.	The datetime value to convert to a date.
`tz`	`tzinfo` or `str` or `Producer`	Optional timezone string (e.g., `"America/New_York"`), offset string (e.g., `"+0600"`), or Python `tzinfo` object. Refer to the timezone database for a list of valid timezone indentifiers. (Default: `"UTC"`).

Returns

An Expression object.

Example

Use date.fromdatetime() to construct a date value from a datetime value:

import relationalai as rai
from relationalai.std import dates

# =====
# SETUP
# =====

model = rai.Model("MyModel")
Event = model.Type("Event")

# Add an event with a time property.
with model.rule():
    Event.add(id=1).set(time=dates.datetime(2020, 1, 1, 1))  # 1:00 AM on January 1, 2020


# =======
# EXAMPLE
# =======

# Set a date property using the time property.
with model.rule():
    event = Event()
    event.set(date=dates.date.fromdatetime(event.time))

with model.query() as select:
    event = Event()
    response = select(event.id, event.time, event.date)

print(response.results)
#    id                time       date
# 0   1 2020-01-01 01:00:00 2020-01-01

Pass a timezone or offset string to the tz parameter to convert the datetime from UTC to a different timezone before extracting the date:

with model.query() as select:
    event = Event()
    date1 = dates.date.fromdatetime(event.time, tz="America/New_York")
    date2 = dates.date.fromdatetime(event.time, tz="+0600")
    response = select(event.id, event.time, alias(date1, "date1"), alias(date2, "date2"))

print(response.results)
#    id                time      date1      date2
# 0   1 2020-01-01 01:00:00 2019-12-31 2020-01-01

Refer to the timezone database for a list of valid timezone identifiers.

See Also