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.