Kode sumber untuk django.db.models.functions.datetime
from __future__ import absolute_import
from datetime import datetime
from django.conf import settings
from django.db.models import (
DateField, DateTimeField, IntegerField, TimeField, Transform,
)
from django.db.models.lookups import (
YearExact, YearGt, YearGte, YearLt, YearLte,
)
from django.utils import timezone
from django.utils.functional import cached_property
class TimezoneMixin(object):
tzinfo = None
def get_tzname(self):
# Timezone conversions must happen to the input datetime *before*
# applying a function. 2015-12-31 23:00:00 -02:00 is stored in the
# database as 2016-01-01 01:00:00 +00:00. Any results should be
# based on the input datetime not the stored datetime.
tzname = None
if settings.USE_TZ:
if self.tzinfo is None:
tzname = timezone.get_current_timezone_name()
else:
tzname = timezone._get_timezone_name(self.tzinfo)
return tzname
[docs]class Extract(TimezoneMixin, Transform):
lookup_name = None
def __init__(self, expression, lookup_name=None, tzinfo=None, **extra):
if self.lookup_name is None:
self.lookup_name = lookup_name
if self.lookup_name is None:
raise ValueError('lookup_name must be provided')
self.tzinfo = tzinfo
super(Extract, self).__init__(expression, **extra)
def as_sql(self, compiler, connection):
sql, params = compiler.compile(self.lhs)
lhs_output_field = self.lhs.output_field
if isinstance(lhs_output_field, DateTimeField):
tzname = self.get_tzname()
sql, tz_params = connection.ops.datetime_extract_sql(self.lookup_name, sql, tzname)
params.extend(tz_params)
elif isinstance(lhs_output_field, DateField):
sql = connection.ops.date_extract_sql(self.lookup_name, sql)
elif isinstance(lhs_output_field, TimeField):
sql = connection.ops.time_extract_sql(self.lookup_name, sql)
else:
# resolve_expression has already validated the output_field so this
# assert should never be hit.
assert False, "Tried to Extract from an invalid type."
return sql, params
def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
copy = super(Extract, self).resolve_expression(query, allow_joins, reuse, summarize, for_save)
field = copy.lhs.output_field
if not isinstance(field, (DateField, DateTimeField, TimeField)):
raise ValueError('Extract input expression must be DateField, DateTimeField, or TimeField.')
# Passing dates to functions expecting datetimes is most likely a mistake.
if type(field) == DateField and copy.lookup_name in ('hour', 'minute', 'second'):
raise ValueError(
"Cannot extract time component '%s' from DateField '%s'. " % (copy.lookup_name, field.name)
)
return copy
@cached_property
def output_field(self):
return IntegerField()
[docs]class ExtractWeekDay(Extract):
"""
Return Sunday=1 through Saturday=7.
To replicate this in Python: (mydatetime.isoweekday() % 7) + 1
"""
lookup_name = 'week_day'
DateField.register_lookup(ExtractYear)
DateField.register_lookup(ExtractMonth)
DateField.register_lookup(ExtractDay)
DateField.register_lookup(ExtractWeekDay)
TimeField.register_lookup(ExtractHour)
TimeField.register_lookup(ExtractMinute)
TimeField.register_lookup(ExtractSecond)
DateTimeField.register_lookup(ExtractYear)
DateTimeField.register_lookup(ExtractMonth)
DateTimeField.register_lookup(ExtractDay)
DateTimeField.register_lookup(ExtractWeekDay)
DateTimeField.register_lookup(ExtractHour)
DateTimeField.register_lookup(ExtractMinute)
DateTimeField.register_lookup(ExtractSecond)
ExtractYear.register_lookup(YearExact)
ExtractYear.register_lookup(YearGt)
ExtractYear.register_lookup(YearGte)
ExtractYear.register_lookup(YearLt)
ExtractYear.register_lookup(YearLte)
class TruncBase(TimezoneMixin, Transform):
arity = 1
kind = None
tzinfo = None
def __init__(self, expression, output_field=None, tzinfo=None, **extra):
self.tzinfo = tzinfo
super(TruncBase, self).__init__(expression, output_field=output_field, **extra)
def as_sql(self, compiler, connection):
inner_sql, inner_params = compiler.compile(self.lhs)
# Escape any params because trunc_sql will format the string.
inner_sql = inner_sql.replace('%s', '%%s')
if isinstance(self.output_field, DateTimeField):
tzname = self.get_tzname()
sql, params = connection.ops.datetime_trunc_sql(self.kind, inner_sql, tzname)
elif isinstance(self.output_field, DateField):
sql = connection.ops.date_trunc_sql(self.kind, inner_sql)
params = []
else:
raise ValueError('Trunc only valid on DateField or DateTimeField.')
return sql, inner_params + params
def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
copy = super(TruncBase, self).resolve_expression(query, allow_joins, reuse, summarize, for_save)
field = copy.lhs.output_field
# DateTimeField is a subclass of DateField so this works for both.
assert isinstance(field, DateField), (
"%r isn't a DateField or DateTimeField." % field.name
)
# If self.output_field was None, then accessing the field will trigger
# the resolver to assign it to self.lhs.output_field.
if not isinstance(copy.output_field, (DateField, DateTimeField)):
raise ValueError('output_field must be either DateField or DateTimeField')
# Passing dates to functions expecting datetimes is most likely a
# mistake.
if type(field) == DateField and (
isinstance(copy.output_field, DateTimeField) or copy.kind in ('hour', 'minute', 'second')):
raise ValueError("Cannot truncate DateField '%s' to DateTimeField. " % field.name)
return copy
def convert_value(self, value, expression, connection, context):
if isinstance(self.output_field, DateTimeField):
if settings.USE_TZ:
if value is None:
raise ValueError(
"Database returned an invalid datetime value. "
"Are time zone definitions for your database and pytz installed?"
)
value = value.replace(tzinfo=None)
value = timezone.make_aware(value, self.tzinfo)
elif isinstance(value, datetime):
# self.output_field is definitely a DateField here.
value = value.date()
return value
[docs]class Trunc(TruncBase):
def __init__(self, expression, kind, output_field=None, tzinfo=None, **extra):
self.kind = kind
super(Trunc, self).__init__(expression, output_field=output_field, tzinfo=tzinfo, **extra)
[docs]class TruncDate(TruncBase):
lookup_name = 'date'
@cached_property
def output_field(self):
return DateField()
def as_sql(self, compiler, connection):
# Cast to date rather than truncate to date.
lhs, lhs_params = compiler.compile(self.lhs)
tzname = timezone.get_current_timezone_name() if settings.USE_TZ else None
sql, tz_params = connection.ops.datetime_cast_date_sql(lhs, tzname)
lhs_params.extend(tz_params)
return sql, lhs_params
[docs]class TruncHour(TruncBase):
kind = 'hour'
@cached_property
def output_field(self):
return DateTimeField()
[docs]class TruncMinute(TruncBase):
kind = 'minute'
@cached_property
def output_field(self):
return DateTimeField()
[docs]class TruncSecond(TruncBase):
kind = 'second'
@cached_property
def output_field(self):
return DateTimeField()
DateTimeField.register_lookup(TruncDate)
