[Serializer] Fix denormalizing date intervals having both weeks and days

[oneNevan]

Q	A
Branch?	5.4
Bug fix?	yes
New feature?	no
Deprecations?	no
Issues	Fix #47629
License	MIT

Added support for date periods having both W and D period designators combined together (which is valid duration for ISO 8601-2). Starting from PHP 8 this is supported by \DateTimeInterval, see https://bugs.php.net/bug.php?id=61366 for reference

[mtarld]

So, to make it work, we need to update the format.

Maybe it could be great to create as well a PR targeting 7.1 to update the format const value, WDYT?

[nicolas-grekas]

LGTM once comments are fixed.

[nicolas-grekas]

Thank you @oneNevan.

[oneNevan]

So, to make it work, we need to update the format.

Maybe it could be great to create as well a PR targeting 7.1 to update the format const value, WDYT?

@mtarld Regarding this, I agree it does make sense, but there is one thing to consider - adding %wW to FORMAT_KEY constant by default would break normalization as DateInterval::format does not support weeks, php docs does not provide it either https://www.php.net/manual/en/dateinterval.format.php - no weeks available :)
Which means we can only use W when denormalizing values from period strings into DateInterval instance.

So, it looks like if we want to support weeks out of the box, we would have to split FORMAT_KEY constant, into two constants: one for normalizer (without %wW), and another one for denormalizer (with %wW).

At this point I wanted to fix the regular expression at least, so that devs could use custom format if they deal with periods having weeks (as I do), but I'm not sure if it worth changing the current default format to support it out of the box, do you think it makes sense?

[mtarld]

Indeed, it sounds like an edge case finally. I think that we might keep it like that, thank you for that feedback 🙂