本文整理匯總了Python中django.db.models.aggregates.Variance方法的典型用法代碼示例。如果您正苦於以下問題：Python aggregates.Variance方法的具體用法？Python aggregates.Variance怎麽用？Python aggregates.Variance使用的例子？那麽, 這裏精選的方法代碼示例或許可以為您提供幫助。您也可以進一步了解該方法所在類django.db.models.aggregates的用法示例。
在下文中一共展示了aggregates.Variance方法的4個代碼示例，這些例子默認根據受歡迎程度排序。您可以為喜歡或者感覺有用的代碼點讚，您的評價將有助於係統推薦出更棒的Python代碼示例。
示例1: check_expression_support
# 需要導入模塊: from django.db.models import aggregates [as 別名]
# 或者: from django.db.models.aggregates import Variance [as 別名]
def check_expression_support(self, expression):
bad_fields = (fields.DateField, fields.DateTimeField, fields.TimeField)
bad_aggregates = (aggregates.Sum, aggregates.Avg, aggregates.Variance, aggregates.StdDev)
if isinstance(expression, bad_aggregates):
for expr in expression.get_source_expressions():
try:
output_field = expr.output_field
except FieldError:
# Not every subexpression has an output_field which is fine
# to ignore.
pass
else:
if isinstance(output_field, bad_fields):
raise NotImplementedError(
'You cannot use Sum, Avg, StdDev, and Variance '
'aggregations on date/time fields in sqlite3 '
'since date/time is saved as text.'
) 示例2: check_expression_support
# 需要導入模塊: from django.db.models import aggregates [as 別名]
# 或者: from django.db.models.aggregates import Variance [as 別名]
def check_expression_support(self, expression):
bad_fields = (fields.DateField, fields.DateTimeField, fields.TimeField)
bad_aggregates = (aggregates.Sum, aggregates.Avg, aggregates.Variance, aggregates.StdDev)
if isinstance(expression, bad_aggregates):
for expr in expression.get_source_expressions():
try:
output_field = expr.output_field
except FieldError:
# Not every subexpression has an output_field which is fine
# to ignore.
pass
else:
if isinstance(output_field, bad_fields):
raise utils.NotSupportedError(
'You cannot use Sum, Avg, StdDev, and Variance '
'aggregations on date/time fields in sqlite3 '
'since date/time is saved as text.'
) 示例3: check_expression_support
# 需要導入模塊: from django.db.models import aggregates [as 別名]
# 或者: from django.db.models.aggregates import Variance [as 別名]
def check_expression_support(self, expression):
bad_fields = (fields.DateField, fields.DateTimeField, fields.TimeField)
bad_aggregates = (aggregates.Sum, aggregates.Avg, aggregates.Variance, aggregates.StdDev)
if isinstance(expression, bad_aggregates):
for expr in expression.get_source_expressions():
try:
output_field = expr.output_field
if isinstance(output_field, bad_fields):
raise NotImplementedError(
'You cannot use Sum, Avg, StdDev, and Variance '
'aggregations on date/time fields in sqlite3 '
'since date/time is saved as text.'
)
except FieldError:
# Not every subexpression has an output_field which is fine
# to ignore.
pass 示例4: check_expression_support
# 需要導入模塊: from django.db.models import aggregates [as 別名]
# 或者: from django.db.models.aggregates import Variance [as 別名]
def check_expression_support(self, expression):
bad_fields = (fields.DateField, fields.DateTimeField, fields.TimeField)
bad_aggregates = (aggregates.Sum, aggregates.Avg, aggregates.Variance, aggregates.StdDev)
if isinstance(expression, bad_aggregates):
try:
output_field = expression.input_field.output_field
if isinstance(output_field, bad_fields):
raise NotImplementedError(
'You cannot use Sum, Avg, StdDev and Variance aggregations '
'on date/time fields in sqlite3 '
'since date/time is saved as text.')
except FieldError:
# not every sub-expression has an output_field which is fine to
# ignore
pass