本文整理汇总了Python中django.db.models.aggregates.Variance方法的典型用法代码示例。如果您正苦于以下问题：Python aggregates.Variance方法的具体用法？Python aggregates.Variance怎么用？Python aggregates.Variance使用的例子？那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类django.db.models.aggregates的用法示例。
在下文中一共展示了aggregates.Variance方法的4个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的Python代码示例。
示例1: check_expression_support
# 需要导入模块: from django.db.models import aggregates [as 别名]
# 或者: from django.db.models.aggregates import Variance [as 别名]
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
# 需要导入模块: from django.db.models import aggregates [as 别名]
# 或者: from django.db.models.aggregates import Variance [as 别名]
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
# 需要导入模块: from django.db.models import aggregates [as 别名]
# 或者: from django.db.models.aggregates import Variance [as 别名]
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
# 需要导入模块: from django.db.models import aggregates [as 别名]
# 或者: from django.db.models.aggregates import Variance [as 别名]
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