Date fields store
datetime values. Times are always stored in UTC, though with appropriate support packages installed (
tzlocal) this can include timezone support.
from marrow.mongo.field import Date
This field type inherits all
Field attributes and represents a singular, scalar date/time value.
Timezone to interpret naive `datetime` objects as utilizing.
Timezone to cast to when retrieving from the database.
Timezone references as utilized by the above may be any of:
The constant string
"naive", resulting in no timezone transformation or alteration of the
tzinfo attribute at all.
The constant string
"local", auto-detecting the host's timezone, requiring the package
localtz be installed. This is most useful if you use
datetime.now() instead of
datetime.utcnow()—please consider updating your code to utilize the UTC variant in preference to this.
tzinfo object, such as those provided by the
Any use of timezone awareness will require the
pytz package be installed, as Python's built-in
tzinfo objects suffer a number of issues. Note also that use of timezones comes with a performance penalty.
Instantiate and assign an instance of this class during construction of a new
Document subclass. Accessing as a class attribute will return a Queryable allowing filtering operations, and access as an instance attribute will return a
datetime cast value.
Date fields are highly aware of date-like objects and how to apply them. For example, you may provide any of the following in place of a pure
MutableMapping instance (such as a
Document instance) with an
_id key whose value is an
ObjectId. The date/time value will be pulled automatically from the
A bare BSON
ObjectId instance, behaving as above.
datetime.timedelta instance whose value will be immediately applied (added to) the result of
A key reason for the above typecasting allowances are to permit natural comparison against those types of objects as admittedly, it'll be unlikely you'll need to populate a date from the ID of a record.
Given a Date field named
modified, you can identify all documents modified in the last 30 days easily and without performing date math yourself: (remembering that the value being queried for becomes static after that comparison)
query = Asset.modified >= timedelta(days=-30)Asset.find(query)