Create empty date for specific format in PHP - php

Question

I would like to get date string filled with zeros for specified date format. I want to use it in case when there is no date given by external API.
Example:
define('DATE_FORMAT', 'Y-m-d H:i:s');
[...]
$date = SomeExternalApi::get_date();
// if date is given it's simple
if(!empty($date)){
$date_obj = DateTime::createFromFormat(SomeExternalApi::SOME_DATE_FORMAT, $date_string);
return $date_obj->format(DATE_FORMAT);
}else{
// SO UGLY BELOW! :( How to use DATE_FORMAT in this case?
return '0000-00-00 00:00:00';
}
I don't want to hardcode "zero string" like in example, because when I change DATE_FORMAT I would like to get zeros formatted new way.
Probably there is no simple way to format "zero string" of date, but maybe someone from this great community has better idea? :)

Answer 1

The best answer for my question is: DON'T GO THIS WAY.
You will never need empty date with zeros - it's super uncommon. The only one place where you can find it is database date field - if there is no date, you will get zeros format. But this will be always the same format, so you can define it as constant and condition as string.
Zeros as I asked are BAD because if you send such zeros through some API to any client like mobile app it has no chance to parse it - it will crash the app without catching errors.
Instead of having zeros date presentation use:
[when saving] put empty string in database, you can set date field to empty string and this will become zeros, do it with UPDATE mytable SET date = "" WHERE id = 2; and mytable.date field is MySQL timestamp in this example,
[when getting] you will get zeros with SELECT date FROM mytable WHERE id = 2;, so define it in your code as constant string 0000-00-00 00:00:00 and equal with returning value from db,
[when response of API] if date is empty return false instead of zeros. Mobile app can check if it's false and try to parse it in any other case. It's the best way to keep empty date and is super simple to check in any format by any language. Lot of simpler than trying to parse some strange zeros format.
Generally if I find date by condition like in example I return false and every single client using this API is happy with it:
if(empty($date)){return false;}

Answer 2

Dates and times in PHP are represented with a UNIX timestamp. The range of possible dates this can represent is not capable of representing the timestamp '0000-00-00 00:00:00' on a 32-bit system (it's over 2000 years ago). Also, actually creating a DateTime representing this single timestamp is probably pretty pointless, the values it represents are unchanging.
However, you could do this by defining absolute values for every sensible format character and using strtr() to convert them to their specific values.
Short example using your example input format:
$placeholders = array(
'Y' => '0000',
'm' => '00',
'd' => '00',
'H' => '00',
'i' => '00',
's' => '00'
);
return strtr(DATE_FORMAT, $placeholders);
However, this could start to get messy when you are dealing with the format elements that represent textual elements such as D. Personally I'd probably pick a default format and use that, as your code in the question shows.