[4.1] Use the date function in calendar field

[laoneo]

Pull Request for Issue #34952 and takeover from #36395.

Summary of Changes

The calendar field uses the strftime to format a date. This function got deprecated in PHP 8.1 and will be removed in 9. This pr uses the widely accepted date function.
There are probably edge cases for format conversion, which are not covered by this pr, but can be added later.

Full credit goes to @PhilETaylor, I was just taking it over and made some small modifications.

Testing Instructions

• Create a new article in the back end
• Click on the publishing tab

Actual result BEFORE applying this Pull Request

The following message is displayed:
Deprecated: Function strftime() is deprecated in /libraries/src/Form/Field/CalendarField.php on line 277

Expected result AFTER applying this Pull Request

No error message.

[tecpromotion]

I have tested this item ✅ successfully on fca7309

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/37329.}

[brianteeman]

Surely this has to go in 4.2

[BPBlueprint]

I have tested this item ✅ successfully on fca7309

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/37329.}

[laoneo]

rtc

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/37329.}

[laoneo]

rtc

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/37329.}

[MacJoom]

I have tested this item ✅ successfully on fca7309

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/37329.}

[bembelimen]

Surely this has to go in 4.2

Yes, or 5.0

[laoneo]

If this has to go into 5, then Joomla 4 will never be able to run on PHP 9. If it has to go into 4.2, then I suggest an alternative parameter where extension developers can define a format in normal PHP date format. Something like date_format. So the tag would look like:

<field
	name="begin"
	type="calendar"
	label="COM_BANNERS_BEGIN_LABEL"
	hint="COM_BANNERS_BEGIN_HINT"
	format="%Y-%m-%d"
	date_format="Y-m-d"
	filter="user_utc"
/>

Extension developers can then still use the normal format parameter to keep backwards compatibility with Joomla 3.

What do you guys think?

[brianteeman]

If you go down the route of the extra date_format then you should also update all date fields in joomla so that they are using the new way and nothing in core is using the old and presumably deprecated method.

@nibra See I think I understand now your comments in the RFC

[joomdonation]

Actually, we can use a hidden parameter filterFormat

joomla-cms/libraries/src/Form/Field/CalendarField.php

Line 118 in f019ec9

case 'filterFormat':

. It is not documented, but used on all of our calendar form fields when translateformat="true" , see https://github.com/joomla/joomla-cms/blob/4.1-dev/libraries/src/Form/Field/CalendarField.php#L207

So Calendar Form fields from core will still work as how it is. For third party extensions, we can just add filterFormat attribute with the right value and it is working OK, too. If the attribute is not available, we can use the code to convert format like how we are doing in this PR (maybe just for PHP >= 8.1.0)

[laoneo]

@joomdonation can you make an alternative pr with the filterFormat? But please make it compatible with all PHP versions.

[joomdonation]

@laoneo If it is OK to make PR without writing unit test, I will give it a try (I don't know how to write unit tests at the moment). Also, I will have to borrow the code of strftimeFormatToDateFormat method in this PR.

[laoneo]

Sure

[laoneo]

CLosing in favor of #37373.