auto generated purchase order number base from year in laravel - php

Question

I have this code which should generate purchase number automatically with year attached to the number.
$record = Ponumbers::latest()->first();
$expNum = explode('-', $record->purchase_num);
//check first day in a year
if ( date('l',strtotime(date('Y-01-01'))) ){
$nextPoNumber = 'po'.date('Y').'-000001';
} else {
//increase 1 with last invoice number
$nextPoNumber = $expNum[0].'-'. $expNum[1]+1;
}
but it doesn't seems to work because it display only the this,
I am guessing it only displayed what's in this line
$nextPoNumber = 'po'.date('Y').'-000001';
any suggestion? thanks you so much in advance!

Answer 1

date('l',strtotime(date('Y-01-01'))) returns first weekday name for 2019, which is Tuesday. That is truthy value so the if is always true and $nextPoNumber is always po2019-000001.
If I understand your code correctly this is what you like it to do:
$record = Ponumbers::latest()->first();
$expNum = explode('-', $record->purchase_num);
$nextPoNumber = 'po'.date('Y').'-'.sprintf("%06d",$expNum[1]+1);

Answer 2

Try this :
$record = Ponumbers::latest()->first();
$expNum = explode('-', $record->purchase_num);
//check first day in a year
$first_day = gmdate('j', strtotime('first day of january this year'));
if (date('j') == $first_day){
$nextPoNumber = 'po'.date('Y').'-000001';
} else {
//increase 1 with last invoice number
$nextPoNumber = $expNum[0].'-'. $expNum[1]+1;
}