Converting date from HTML form to datetime

Using Django
1

The following code works fine in converting two search criteria to datetimes:

            for _key in request.GET:
                if _key == "txtCriteriaDateFrom":
                    _dateFromStr = request.GET[_key]
                    _dateFrom = datetime.strptime(_dateFromStr, '%Y-%m-%d') 
                if _key == "txtCriteriaDateTo":
                    _dateToStr = request.GET[_key]
                    _dateTo = datetime.strptime(_dateToStr, '%Y-%m-%d')

The data is coming into the GET object from a <input type=‘date’ control and that wants the Y-m-d format.

I’m just a little concerned that the format is very specific and that makes the above code very brittle and liable to break in the future.

Is there a more generic way of converting a string with a valid datetime format, but which could be any format (the US standard m-d-Y being a good example)?

Or is there a better way of doing this completely?

2

I would say that there really isn’t. You want an unambiguous notation to be used in your forms to prevent misunderstanding such as the difference between “m-d-y” and “d-m-y” - made worse if you allow now for 2-digit years.

Having said that, you do have the DATE_INPUT_FORMATS setting available to you to allow for different formats to be acceptable as input. But that’s only directly useful if you’re assigning those values to a field. (You could look at the implementation to see if there are classes / methods that you could take advantage of.)

3

No, that’s fine, I just wanted to check. I can work the UI error handling around this.

I’m finding my bioinformatic colleagues are entirely optimistic about potential issues like this, whereas I’m entirely cynical…or realistic, depending on viewpoint.

4

The degree of “brittleness” in this case is going to depend upon the front-end building the URL with those query parameters. If it’s user-entered data in a form, they need to be taught what the proper format is.
If it’s being generated from some type of input widget, then yes - there’s a chance that that widget changing might break your code - but that’s a change you would need to know about anyway. In the ideal world, the JS widget being used accepts some type of configuration parameter specifying the supplied data format.