How to set a limit?

Question

CMS

How to make a restriction so that when entering you can enter a number from 1-31, but if the number 0 is entered, then an error was displayed

Answer 1

$year = $intval($year);
return $year > 0 && $year <=31;

Answer 2

Assert::assert($year, 'year')->int()->between(1, 31);

Link to the library
My advice to you: forget about the existence of errors, only exceptions, it will wildly simplify your life.