1
0
mirror of https://github.com/jbranchaud/til synced 2026-07-02 23:58:25 +00:00

Add Parse Relative Time To datetime Object as a Python TIL

This commit is contained in:
jbranchaud
2026-03-08 10:53:04 -05:00
parent e1c3f23975
commit 01f9d89e8e
2 changed files with 64 additions and 1 deletions
+2 -1
View File
@@ -10,7 +10,7 @@ working across different projects via [VisualMode](https://www.visualmode.dev/).
For a steady stream of TILs, [sign up for my newsletter](https://visualmode.kit.com/newsletter). For a steady stream of TILs, [sign up for my newsletter](https://visualmode.kit.com/newsletter).
_1754 TILs and counting..._ _1755 TILs and counting..._
See some of the other learning resources I work on: See some of the other learning resources I work on:
@@ -1053,6 +1053,7 @@ If you've learned something here, support my efforts writing daily TILs by
- [Keep A Tally With collections.Counter](python/keep-a-tally-with-collections-counter.md) - [Keep A Tally With collections.Counter](python/keep-a-tally-with-collections-counter.md)
- [Load A File Into The Python REPL](python/load-a-file-into-the-python-repl.md) - [Load A File Into The Python REPL](python/load-a-file-into-the-python-repl.md)
- [Override The Boolean Context Of A Class](python/override-the-boolean-context-of-a-class.md) - [Override The Boolean Context Of A Class](python/override-the-boolean-context-of-a-class.md)
- [Parse Relative Time To datetime Object](python/parse-relative-time-to-datetime-object.md)
- [Store And Access Immutable Data In A Tuple](python/store-and-access-immutable-data-in-a-tuple.md) - [Store And Access Immutable Data In A Tuple](python/store-and-access-immutable-data-in-a-tuple.md)
- [Test A Function With Pytest](python/test-a-function-with-pytest.md) - [Test A Function With Pytest](python/test-a-function-with-pytest.md)
- [Use pipx To Install End User Apps](python/use-pipx-to-install-end-user-apps.md) - [Use pipx To Install End User Apps](python/use-pipx-to-install-end-user-apps.md)
@@ -0,0 +1,62 @@
# Parse Relative Time To datetime Object
I was looking for an out-of-the-box solution for parsing natural language,
relative time strings (e.g. `'33 minutes ago'`) into valid `datetime` objects.
The best library for this is
[`dateparser`](https://dateparser.readthedocs.io/en/latest/).
While it is as easy to use this as _import_ then _parse_:
```python
>>> import dateparser
>>> dateparser.parse('33 minutes ago')
datetime.datetime(2026, 3, 7, 23, 19, 9, 17855)
```
There is more to it if we need to deal with timezones.
In my use case, I wanted to my `datetime` object to be timezone-aware and I
wanted to store it in `UTC`.
As is, the above simple `datetime` object is not `tzaware`, meaning it doesn't
have any `tzinfo` attached to it.
```python
>>> dateparser.parse('33 minutes ago').tzinfo is not None
False
```
We need to pass some additional settings during `parse`.
```python
>>> settings = {'RETURN_AS_TIMEZONE_AWARE': True}
>>> dateparser.parse('33 minutes ago', settings=settings)
>>> _
datetime.datetime(2026, 3, 8, 9, 53, 36, 225099, tzinfo=zoneinfo.ZoneInfo(key='America/Chicago'))
>>> settings['TO_TIMEZONE'] = 'UTC'
>>> dateparser.parse('33 minutes ago', settings=settings)
>>> _
datetime.datetime(2026, 3, 8, 14, 54, 47, 34041, tzinfo=<StaticTzInfo 'UTC'>)
```
The first step to getting a `datetime` object that is `tzaware` is to set
`RETURN_AS_TIMEZONE_AWARE` to `True`. That picks up the locale setting of the
system it is running on -- in my case, I'm in Chicago.
I said I wanted to store this as UTC though. That means I need to pass an
additional setting `TO_TIMEZONE` with a value of `'UTC'` which will translate
the `datetime` from my local time to UTC -- notice the 5 hour difference from
`9` to `14`.
Storing `datetime` details like this with timezone info _as_ UTC is nice because
it keeps everything consistent at the storage layer and then at the presentation
layer I can always convert it right back to the local timezone with
`astimezone`.
```python
>>> _.astimezone()
datetime.datetime(2026, 3, 8, 9, 54, 47, 34041, tzinfo=datetime.timezone(datetime.timedelta(days=-1, seconds=68400), 'CDT'))
```
See the [`datetime` docs](https://docs.python.org/3/library/datetime.html) for
more details.