Weird problem writing json result to file

I'm trying to make sure I only pull information from an external resource when it's not already there, and therefore I'm trying to write the result to a file if the file isn't already there.

I use the following code:

    if (file_exists($_SERVER['DOCUMENT_ROOT'].'/utilities/holidays_'.$file_date.'.json')) {
       $get_holidays_year_and_month = file_get_contents($_SERVER['DOCUMENT_ROOT'].'/utilities/holidays_'.$file_date.'.json', true);
     } else {
       $write_to_file = json_decode(file_get_contents('http://holidayapi.com/v1/holidays?country=NO&year='.$request_year.'&pretty'));
       file_put_contents($_SERVER['DOCUMENT_ROOT'].'/utilities/holidays_'.$file_date.'.json',$write_to_file);
       $get_holidays_year_and_month = file_get_contents($_SERVER['DOCUMENT_ROOT'].'/utilities/holidays_'.$file_date.'.json',true);
     }

PHP:

It works, apart from the fact that it doesn't write anything to the file - it creates the file, but the file is empty, and I'm wondering if that's because it returns a stdObject - if that's it, how do I create something I can put into the file?

No errors returned, nothing says it doesn't work, but for some reason, there's nothing in the file after it gets written.

If I var_dump() the $write_to_file variable before the file_put_contents(), it contains the expected result.

 

And, of course, right after I post it here, I get an epiphany, and remember what I've forgotten. Here's working code:

    if (file_exists($_SERVER['DOCUMENT_ROOT'].'/utilities/holidays_'.$file_date.'.json')) {
       $get_holidays_year_and_month = unserialize(file_get_contents($_SERVER['DOCUMENT_ROOT'].'/utilities/holidays_'.$file_date.'.json', true));
     } else {
       $write_to_file = json_decode(file_get_contents('http://holidayapi.com/v1/holidays?country=NO&year='.$request_year.'&pretty'));
       file_put_contents($_SERVER['DOCUMENT_ROOT'].'/utilities/holidays_'.$file_date.'.json',serialize($write_to_file));
       $get_holidays_year_and_month = unserialize(file_get_contents($_SERVER['DOCUMENT_ROOT'].'/utilities/holidays_'.$file_date.'.json',true));
     }

PHP:

serialize() and unserialize(), if you can't see the difference.

 

Yes, such things happen)) It's useful sometimes to take a break and the decision of the problem appears by itself)

and let me give you just a little advice - I think that way will be little better

if (!file_exists($_SERVER['DOCUMENT_ROOT'].'/utilities/holidays_'.$file_date.'.json')) {
    $write_to_file = json_decode(file_get_contents('http://holidayapi.com/v1/holidays?country=NO&year='.$request_year.'&pretty'));
    file_put_contents($_SERVER['DOCUMENT_ROOT'].'/utilities/holidays_'.$file_date.'.json',serialize($write_to_file));
}
$get_holidays_year_and_month = unserialize(file_get_contents($_SERVER['DOCUMENT_ROOT'].'/utilities/holidays_'.$file_date.'.json', true));

PHP:

 

True - I have a tendency to overcomplicate some things sometimes