dateutil functions for Datasette

Install this plugin in the same environment as Datasette.

$ datasette install datasette-dateutil

This function adds custom SQL functions that expose functionality from the dateutil Python library.

Once installed, the following SQL functions become available:

• dateutil_parse(text) - returns an ISO8601 date string parsed from the text, or null if the input could not be parsed. dateutil_parse("10 october 2020 3pm") returns 2020-10-10T15:00:00.
• dateutil_parse_fuzzy(text) - same as dateutil_parse() but this also works against strings that contain a date somewhere within them - that date will be returned, or null if no dates could be found. dateutil_parse_fuzzy("This is due 10 september") returns 2020-09-10T00:00:00 (but will start returning the 2021 version of that if the year is 2021).
• dateutil_easter(year) - returns the date for Easter in that year, for example dateutil_easter("2020") returns 2020-04-12.

The dateutil_parse() and dateutil_parse_fuzzy() functions both follow the American convention of assuming that 1/2/2020 lists the month first, evaluating this example to the 2nd of January.

If you want to assume that the day comes first, use these two functions instead:

• dateutil_parse_dayfirst(text)
• dateutil_parse_fuzzy_dayfirst(text)

To set up this plugin locally, first checkout the code. Then create a new virtual environment:

cd datasette-dateutil
python3 -mvenv venv
source venv/bin/activate

Or if you are using pipenv:

pipenv shell

Now install the dependencies and tests:

pip install -e '.[test]'

To run the tests:

pytest