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# Copyright (c) 2014 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
# This module contains some commonly used time conversion function.
import datetime
import time
# This format is used to parse datetime value in MySQL database and should not
# be modified.
TIME_FMT = '%Y-%m-%d %H:%M:%S'
TIME_FMT_MICRO = '%Y-%m-%d %H:%M:%S.%f'
def time_string_to_datetime(time_string, handle_type_error=False):
"""Convert a string of time to a datetime object.
The format of date string must match '%Y-%m-%d %H:%M:%S' or
'%Y-%m-%d %H:%M:%S.%f'.
@param time_string: String of date, e.g., 2014-12-05 15:32:45
@param handle_type_error: Set to True to prevent the method raise
TypeError if given time_string is corrupted. Default is False.
@return: A datetime object with time of the given date string.
return datetime.datetime.strptime(time_string, TIME_FMT)
except ValueError:
return datetime.datetime.strptime(time_string, TIME_FMT_MICRO)
except TypeError:
if handle_type_error:
return None
def date_string_to_epoch_time(date_string):
"""Parse a date time string into seconds since the epoch.
@param date_string: A string, formatted according to `TIME_FMT`.
@return The number of seconds since the UNIX epoch, as a float.
return time.mktime(time.strptime(date_string, TIME_FMT))
def epoch_time_to_date_string(epoch_time, fmt_string=TIME_FMT):
"""Convert epoch time (float) to a human readable date string.
@param epoch_time The number of seconds since the UNIX epoch, as
a float.
@param fmt_string: A string describing the format of the datetime
string output.
@returns: string formatted in the following way: "yyyy-mm-dd hh:mm:ss"
if epoch_time:
return datetime.datetime.fromtimestamp(
return None
def to_epoch_time(value):
"""Convert the given value to epoch time.
Convert the given value to epoch time if it is a datetime object or a string
can be converted to datetime object.
If the given value is a number, this function assume the value is a epoch
time value, and returns the value itself.
@param value: A datetime object or a number.
@returns: epoch time if value is datetime.datetime,
otherwise returns the value.
@raise ValueError: If value is not a datetime object or a number.
if isinstance(value, basestring):
value = time_string_to_datetime(value)
if isinstance(value, datetime.datetime):
return time.mktime(value.timetuple()) + 0.000001 * value.microsecond
if not isinstance(value, int) and not isinstance(value, float):
raise ValueError('Value should be a datetime object, string or a '
'number. Unexpected value: %s.' % value)
return value