Python - Working With Date Values

Applies to TestComplete 15.0, last modified on October 14, 2021

This topic explains how to work with date values in Python and provides examples of date operations. It contains the following sections:

Basics

When writing scripts we often deal with dates. There are certain date value formats and TestComplete routines that help handle dates.

Since the TestComplete scripting engine only supports OLE-compatible data types, the date-time values are implemented as floating-point variant values in a special format. The integer part of this value represents the number of days that have passed since December 30, 1899. The number after the decimal separator represents the fraction of a 24-hour period that has elapsed. However, you do not have to understand what these floating-point values represent. TestComplete provides several routines that help you convert these values to their string representation (see below).

Below are some examples of date-time values and their meaning:

Value Meaning
0.25 December 30, 1899. 6:00 AM
36345.5 July 4, 1999. 12:00 PM
39094.65625 January 12, 2007. 3:45 PM

When you are only working with date values the fractional part can be omitted.

Objects and Functions for Working With Date Values

TestComplete has the aqDateTime object that contains methods that can be useful when operating with dates.

Method Description
AddDays Adds or subtracts the specified number of days to (from) the given date.
AddMonths Adds or subtracts the specified number of months to (from) the given date.
AddTime Adds or subtracts the specified number of days, hours, minutes and seconds to (from) the given date.
Compare Compares two specified date/time values.
GetDay Returns the ordinal number of a day in a month.
GetDayOfWeek Returns the day of the week for the specified date.
GetDayOfYear Returns the ordinal number of a day in a year.
GetMonth Returns the month number of the specified date.
GetYear Returns the year number of the specified date.
IsLeapYear Indicates whether the specified year is a leap year.
Now Returns the current date and time.
SetDateElements Returns the Date variable having the specified year, month and day.
SetDateTimeElements Returns the Date variable having the specified date and time portions.
SetSystemDateTime Assigns the specified date and time as the system date and time.
Today Returns the current date.

One more object, aqConvert, provides methods to convert strings between date values and their string equivalents:

Method Description
DateTimeToFormatStr Converts the given date value to a string using the specified format.
DateTimeToStr Converts the given date value to a string.
StrToDate Converts the specified string to a date value.
StrToDateTime Converts the specified string to a date/time value.

The aqDateTime and aqConvert objects are available for all supported scripting languages, so that you can use them to operate with date values regardless of the chosen language.

Getting Current Date

There are two routines that return the current date: Today and Now. The difference between them is that the value returned by the Now routine includes both the date and time parts, whereas the Date routine returns only the date part. The script below demonstrates how to use them.

Python

def GetDate():
  # Obtain the current date 
  TodayValue = aqDateTime.Today()

  # Obtain the current date and time 
  NowValue = aqDateTime.Now()
  
  # Convert the returned date/time values to the string values 
  StringTodayValue = aqConvert.DateTimeToStr(TodayValue)
  StringNowValue = aqConvert.DateTimeToStr(NowValue)

  # Post the converted values to the log 
  Log.Message("The date obtained from the Today routine is " + StringTodayValue)
  Log.Message("The date obtained from the Now routine is " + StringNowValue)
  
  # Convert the floating-point values to the string values 
  VariantTodayValue = aqConvert.FloatToStr(TodayValue)
  VariantNowValue = aqConvert.FloatToStr(NowValue)

  # Post the converted values to the log 
  Log.Message("The variant representation of TodayValue is " + VariantTodayValue)
  Log.Message("The variant representation of NowValue is " + VariantNowValue)

Getting Tomorrow’s and Yesterday’s Dates

The sample below demonstrates how the aqDateTime object can be used to calculate tomorrow's date. The current date is obtained via the aqDateTime.Today method. Then the current date value is incremented via the aqDateTime.AddDays method. The DateTimeToStr method of the aqConvert object is used to convert the date value to a string that is posted to the TestComplete log.

Python

def TomorrowDate():
  # Obtain the current date 
  CurrentDate = aqDateTime.Today()

  # Convert the date/time value to a string and post it to the log 
  Today = aqConvert.DateTimeToStr(CurrentDate)
  Log.Message("Today is " + Today)

  # Calculate the tomorrow's date, convert the returned date to a string and post this string to the log 
  Tomorrow = aqDateTime.AddDays(CurrentDate, 1)
  ConvertedTomorrowDate = aqConvert.DateTimeToStr(Tomorrow)
  Log.Message("Tomorrow will be " + ConvertedTomorrowDate)
  return Tomorrow

Similarly, you can calculate any date that differs from the current day by a certain amount of days: yesterday, the next or previous week and so on. For example, to get yesterday’s date, you have to pass -1 as the second parameter of the aqDateTime.AddDays method.

Python

def YesterdayDate():
  # Obtain the current date 
  CurrentDate = aqDateTime.Today()

  # Convert the date/time value to a string and post it to the log 
  Today = aqConvert.DateTimeToStr(CurrentDate)
  Log.Message("Today is " + Today)

  # Calculate the yesterday's date, convert the returned date to a string and post this string to the log 
  YesterdayDate = aqDateTime.AddDays(CurrentDate, -1)
  ConvertedYesterdayDate = aqConvert.DateTimeToStr(YesterdayDate)
  Log.Message("Yesterday was " + ConvertedYesterdayDate)

Calculating the Year and Month Duration

Generally, there are 365 days in a calendar year. However, the length of an astronomical year is about 365.242375 days, so, in the course of time, the fractional part would result in an extra day and the calendar year would lag from the astronomical year. To avoid this, the leap year that is 366 days long was invented.

The Gregorian calendar is the current standard calendar in most of the world and it adds a 29th day to February in all years evenly divisible by 4, except for centennial years (those ending in -00), which only receive the extra day if they are evenly divisible by 400. The aqDateTime object has a special method, IsLeapYear, that accepts the year number and returns True if the specified year is a leap year. You can use this method to get the exact number of days in the desired year:

Python

def DaysInYear(YearNo):
  return 365 + aqDateTime.IsLeapYear(YearNo)

In the example above, a Boolean value was added to an integer, since in Python, Booleans have a numerical value of 0 (False) or 1 (True).

Using the IsLeapYear method, you can get the number of days in the month. For all months, except for February, the duration of a month is fixed and is either 30 or 31 days. The duration of February is either 28 or 29 days, depending on whether the current year is a leap year or not. The routine that gets the month duration would be the following:

Python

def DaysInMonth(MonthNo, YearNo):
  if MonthNo == 1 or MonthNo == 3 or MonthNo == 5 or MonthNo == 7 or MonthNo == 8 or MonthNo == 10 or MonthNo == 12:
    return 31
  elif MonthNo == 2:
    if aqDateTime.IsLeapYear(YearNo):
      return 29
    else:
      return 28
  elif MonthNo == 4 or MonthNo == 6 or MonthNo == 9 or MonthNo == 11:
    return 30

Comparing Dates

To compare date/time values, use the aqDateTime.Compare method rather than comparison operators (like ==, >, <, != and others) provided by the scripting engine:

Python

def compare(DateTime1, DateTime2):
  r = aqDateTime.Compare(DateTime1, DateTime2)
  if r > 0:
    # DateTime1 > DateTime2 
    ...
  else:
    if r < 0:
      # DateTime1 < DateTime2 
      ...
    else:
      # DateTime1 == DateTime2 
      ...

This note does not concern the Date objects provided by the Python engine. To compare Date objects, use the features provided by the engine.

Encoding and Decoding Date Values

Since date values are represented as variants, special routines are required for converting a variant value to a calendar date and vice versa. These operations are performed by the SetDateElements, GetYear, GetMonth and GetDay methods of the aqDateTime object. These methods take into account whether the current year is a leap year and the number of days in a month so that the resulting value is guaranteed to be valid. The SetDateElements method accepts the parts of a date and returns a variant date value.

Python

def EncodeDateDemo():
  # Create a Date variable having the specified year, month and day values
  myDate = aqDateTime.SetDateElements(2005, 12, 25)

  # Convert the value of the myDate variable to a string using the specified format and post this string to the log 
  EncodedDate = aqConvert.DateTimeToFormatStr(myDate,"%B/%#d/%Y")
  Log.Message("The encoded date is "+ EncodedDate)

  # Convert the value of the myDate variable to a variant value and post it to the log 
  VariantDate = aqConvert.IntToStr(myDate)
  Log.Message("The variant representation of it is "+ VariantDate)

The GetYear, GetMonth and GetDay methods accept the variant date-time value and return the respective date parts of that value. Below is an example of how to use these routines:

Python

def DecodeDateDemo():
  # Obtain the current date 
  CurrentDate = aqDateTime.Today()

  # Return the parts of the current date value and then post them to the log 
  Year = aqDateTime.GetYear(CurrentDate)
  Month = aqDateTime.GetMonth(CurrentDate)
  Day = aqDateTime.GetDay(CurrentDate)

  Log.Message(str(Day) + " day(s) have passed since the beginning of the " + str(Month) + " month of " + str(Year) + " year.")

Modifying Date Values

Despite the fact that date-time values are represented as floating-point numbers, you cannot explicitly use ordinary arithmetic operators to change dates or times. However, the aqDateTime scripting object provides a number of methods that were especially designed to modify date-time values. These methods are: AddMonths, AddDays and AddTime. The AddTime method allows you to modify the date and time portions at once.

As you may notice from the Getting Tomorrow’s and Yesterday’s Dates section, these methods are used both for incrementing and decrementing date-time values. When a positive number is passed as Month, Days or another parameter, then the resulting value is increased. If the parameter is negative, then the resulting value is decreased.

These methods take into account the number of days in the month, whether the year is a leap year and other aspects of time calculations, which guarantees that the resulting value will be valid.

The code below demonstrates how to use these methods:

Python

def ModifyDates():
    Date = aqDateTime.SetDateElements(2007, 1, 25)

    # Increase the date by 7 days
    # Note the month changing 
    AlteredDate = aqDateTime.AddDays(Date, 7)
    Log.Message("Initial date: " + aqConvert.DateTimeToStr(Date))
    Log.Message("Altered date 1: " + aqConvert.DateTimeToStr(AlteredDate))

    # Increase the date by one month 
    # Note that 28 days were added since the month is February 
    AlteredDate = aqDateTime.AddMonths(AlteredDate, 1)
    Log.Message("Altered date 2: " + aqConvert.DateTimeToStr(AlteredDate))

    # Decrease the date by 1 day
    AlteredDate = aqDateTime.AddTime(AlteredDate, -1, 0, 0, 0)
    Log.Message("Altered date 3: " + aqConvert.DateTimeToStr(AlteredDate))

Dealing With Week Days

Besides recognizing a date, month and year, you may need to know which day of the week a certain date falls on. The aqDateTime.GetDayOfWeek method performs this task. It accepts a variant date and returns the number of the week day that corresponds to it. The returned number ranges between 1 and 7, where 1 corresponds to Sunday, 2 - to Monday, and so on. The sample code below obtains the current date, calculates the day of the week and posts the name of the day to the log.

Python

def DayOfWeekDemo():
  WeekDay = aqDateTime.GetDayOfWeek(aqDateTime.Today())
  if WeekDay == 1:
    DayName = "Sunday"
  elif WeekDay == 2:
    DayName = "Monday"
  elif WeekDay == 3:
    DayName = "Tuesday"
  elif WeekDay == 4:
    DayName = "Wednesday"
  elif WeekDay == 5:
    DayName = "Sunday"
  elif WeekDay == 6:
    DayName = "Thursday"
  elif WeekDay == 7:
    DayName = "Friday"
  elif WeekDay == 8:
    DayName = "Saturday"
  Log.Message("Today is " + DayName)
Note: The GetDayOfWeek method uses the United States system of week notation where the week is considered to start on Sunday and end on Saturday. However, the ISO 8601 “Data elements and interchange formats - Information interchange - Representation of dates and times” standard recommends another system of week notation. In this system, the week starts on Monday and ends on Sunday. To convert a US week day number to ISO 8601, you can use the following routine:

Python

def ISODayOfWeek(InputDate):
  ReturnDate = aqDateTime.GetDayOfWeek(InputDate) - 1
  if (ReturnDate == 0) :
    ReturnDate = 7
  return ReturnDate;
The result of this function is also an integer number, but 1 corresponds to Monday, 2 to Tuesday and so on.

In addition to the day of the week, you can determine the dates when the week starts and ends. This can be done using the following two routines. Here, the number of a week day is subtracted from the specified date to get the beginning of the week, and to get the end of the week, six days are added to the calculated date.

Python

def StartOfWeek (InputDate):
  # If the input parameter is omitted then current date is taken 
  if InputDate == None: 
    InputDate = aqDateTime.Today()

  # Using US week day number 
  return aqDateTime.AddDays(InputDate, - aqDateTime.GetDayOfWeek(InputDate) + 1)

  # Using ISO week day number 
  # return aqDateTime.AddDays(InputDate, - ISODayOfWeek(InputDate) + 1)

def EndOfWeek (InputDate):
  # If the input parameter is omitted then current date is taken 
  if InputDate == None:
    InputDate = aqDateTime.Today()

  # Using US week day number 
  return aqDateTime.AddDays(InputDate, - aqDateTime.GetDayOfWeek(InputDate) + 7)

  # Using ISO week day number 
  # return aqDateTime.AddDays(InputDate, - ISODayOfWeek(InputDate) + 7)
Note: Since the routines use the aqDateTime.GetDayOfWeek method, which returns a US week day number, the dates returned by the routines are Sunday and Saturday. To use the ISO 8601 week day notation, you should use the last code line where the aqDateTime.GetDayOfWeek call is replaced with a call to the ISODayOfWeek function. (The code of the ISODayOfWeek function is provided in the note above.) In this case, the first routine will return the date that falls on Monday and the second routine - the date that falls on Sunday.

Another frequent operation when dealing with dates is calculating the number of weeks that have passed since the beginning of the year. First, you should clarify what week should be considered as the first week of the year. According to the ISO 8601 standard, the first week of a year is a week with the majority (four or more) of days in the starting year. In our case, it is better to use another definition of the first week: the week with the date January, 4th.

Below is a routine that calculates the week number in compliance with this rule. It accepts the date, determines whether the week is the first one, and then calculates the week number as a difference between the end of specified week and the end of the first week divided by 7..

Python

def WeekNumber(InputDate):
  YearNo = aqDateTime.GetYear(InputDate)
  EndOfFirstWeek = EndOfWeek(aqDateTime.SetDateElements(YearNo,1,4))
  EndOfCurrentWeek = EndOfWeek(InputDate)
  return 1 + (aqDateTime.GetDayOfYear(EndOfCurrentWeek) - aqDateTime.GetDayOfYear(EndOfFirstWeek)) / 7

Sometimes, it is useful to know on what day of the week the desired month starts or ends. The routines below return the week day numbers that correspond to the beginning and to the end of the month. They have only one input parameter that specifies the date that belongs to the desired month. If the parameter is missing, then the routines return the results for the current month. These routines calculate the day of the month in a similar way the routines above calculate the number of the week.

Python

def StartOfMonthDay (InputDate):
  # If the input parameter is omitted then current date is taken 
  if InputDate == None:
    InputDate = aqDateTime.Today()
  StartDate = aqDateTime.AddDays(InputDate, - aqDateTime.GetDay(InputDate)+1)

  # Using US week day number 
  return aqDateTime.GetDayOfWeek(StartDate)

  # Using ISO week day number 
  # return ISODayOfWeek(StartDate)

def EndOfMonthDay (InputDate):
  # If the input parameter is omitted then current date is taken 
  if InputDate == undefined:
    InputDate = aqDateTime.Today()
  DayNo = aqDateTime.GetDay(InputDate)
  MonthNo = aqDateTime.GetMonth(InputDate)
  YearNo = aqDateTime.GetYear(InputDate)
  EndDate = aqDateTime.AddDays(InputDate, - DayNo + DaysInMonth(MonthNo, YearNo))

  # Using US week day number 
  return aqDateTime.GetDayOfWeek(EndDate)

  # Using ISO week day number 
  # return ISODayOfWeek(EndDate)

See Also

Working With Dates
Python - Working With Time Values
aqDateTime Object

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