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relationalai.std.dates.datetime.fromordinal()

datetime.fromordinal(ordinal: int|Producer) -> Expression

Constructs a UTC datetime value from a Gregorian proleptic ordinal number with the sub-day time components all set to zero. If ordinal is a Producer, then datetime.fromordinal() also acts as a filter and removes non-integer values from the producer. Must be called in a rule or query context.

A Gregorian proleptic ordinal number is given as the number of days since January 1, 0001 (day 1).

Parameters

Name	Type	Description
`ordinal`	`int` or `Producer`	A Gregorian proleptic ordinal number.

Returns

An Expression object.

Example

Use datetime.fromordinal() to construct a UTC datetime value from a Gregorian proleptic ordinal number:

import relationalai as rai
from relationalai.std import dates


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

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

with model.rule():
    Event.add(id=1).set(ordinal=737791)  # January 1, 2021
    Event.add(id=2).set(ordinal="invalid")


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

with model.rule():
    event = Event()
    # datetime.fromordinal() filters out any events with invalid ordinals, so
    # the following only sets the date property for Event 1.
    event.set(date=dates.datetime.fromordinal(event.ordinal))
    # Since Event 2 was filtered above, the following only sets the
    # has_valid_ordinal property for the Event 1.
    event.set(has_valid_ordinal=True)

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

print(response.results)
#    id       date has_valid_ordinal
# 0   1 2021-01-01              True
# 1   2        NaT               NaN

See Also