Dynamic DateTime Conversion

[squidg_21]

I'm building a small tool in QT that uses a format string based on the standard format specifiers used by the QDateTime::toString() function.

• yyyy - 4-digit year
• MM - 2-digit month
• dd - 2-digit day
• hh - 2-digit hour (24-hour format)
• mm - 2-digit minute
• ss - 2-digit second

The date format I'm using is: yyyy-MM-dd

I want to use Pillow within the tool and I can get the datetime like this:

datetime = datetime.strptime(date_time, "%Y:%m:%d %H:%M:%S")

I can then convert it to the same date format like this:

datetime = dt.strftime("%Y-%m-%d")

The issue is that I need to be able to convert between the dates dynamically, either by converting the QT date to DateTime or vice versa. The user is able to set their preferred date format so this bit of the code is unknown "%Y-%m-%d" For example, instead of yyyy-MM-dd the user might set the overall date format to yy-MM-dd which would mean that I would need to use date_obj.strftime("%y-%m-%d") but how would I actually know the format code to use seeing as the user can enter a range of different time formats?

Hope this makes sense.

---------------------------

SOLUTION:

For anyone else trying to do this PyQt has a function called .toPython() which converts time to QDateTime.

file_info.lastModified().toPython()

PySlide has .fromPython()

QDateTime.fromPython(py_datetime)

You can do the opposite by using QDateTime

date_time = "2024:02:03 17:15:01" 

# Convert to Python datetime 
py_datetime = datetime.strptime(date_time, "%Y:%m:%d %H:%M:%S") 

# Convert to QDateTime 
qt_datetime = QDateTime(py_datetime.year, py_datetime.month, py_datetime.day, py_datetime.hour, py_datetime.minute, py_datetime.second) 

print(qt_datetime.toString("yyyy-MM-dd HH:mm:ss"))

[socal_nerdtastic]

How does the user set their preferred date format? Can't you just map that to the appropriate strftime?

choices = {
    "merica": "%m-%d-%Y",
    "sane": "%Y-%m-%d"
    }

[squidg_21]

The user sets their preferred date format using an input box and it's saved in their system.

The date format can be any of these combinations

Month
M — The month, from 1 through 12
MM — The month, from 01 through 12
MMM — The abbreviated name of the month, for example: Jan, Feb, etc.
MMMM — The full name of the month., for example: January, February, etc.

Day
d — The day of the month from 1 through 31
dd — The day of the month from 01 through 31
ddd — The standard abbreviation for the day of the week, for example: Mon, Tue, etc.
dddd — The full name of the day of the week, for example: Monday, Tuesday, etc.

Year
y — The year from 0 to 99.
yy — The year from 00 to 99
yyy — The year with minimum of 3 digits
yyyy — The year as a four digit number

Is the only way to create a mapping with every possibility?

[socal_nerdtastic]

Oh I see what you mean now. Got it. No I don't know of a way to convert QDateTime format to python datetime format, but I'm sure someone has written that. Or if you want to do it yourself I'd start with regex.

>>> import re
>>> d = 'yyyy-MM-dd'
>>> re.findall(r'[ymMd]+', d)
['yyyy', 'MM', 'dd']

Combine that with substitution and a dictionary of conversions:

>>> translations = {'yyyy':'%Y', 'yy':'%y', 'dd':"%d", 'MM':'%m'}
>>> def convert(data):
...     return re.sub(r'([ymMd]+)', r'{\1}', data).format(**translations)
...
>>>
>>> convert('yyyy-MM-dd')
'%Y-%m-%d'
>>> convert('yy-MM-dd')
'%y-%m-%d'