How to use eloquent builder to fetch results twice - php

Question

How do I use one query builder to fetch results twice? With Carbon I have use CarbonImmutable to achieve this but with eloquent, one fetch is affecting the others down the line.
Here is the code.
$expenses = PropertyExpense::with(['bill'])
->where('contractor_id', $supplier);
/* I run this to get balance brought forward */
$oldDebits = $expenses->whereDate('txn_date', '<', $start)
->sum('billed'); //here I get actual bbf value.
/* Then I run this to get the debits for the start and end period */
$debits = $expenses
->whereDate('txn_date', '>=', $start)
->whereDate('txn_date', '<=', $end)
->get(); //Here I get empty array. Which should not be the case.
When I remove the $oldDebits Section, I get the Collection of all debits as expected.
I have even rewritten the code to temporarily assign expenses to another variable before executing the sum to no avail. Here.
$olderDebits = $expenses;
$oldDebits = $olderDebits->whereDate('txn_date', '<', $start)->sum('billed');
When I ran this, am still getting the same results: correct $oldDebits and an empty collection for $debits.
Any assistance?
Am using Laravel V9 and PHP 8.1.

Answer 1

That is because you ->whereDate() on to the same variable which is $expenses.
In your case, you should clone the query builder before execute it.
Such as
$expenses = PropertyExpense::with(['bill'])->where('contractor_id', $supplier);
$oldDebits = (clone $expenses)->whereDate('txn_date', '<', $start)->sum('billed');
$debits = (clone $expenses)
->whereDate('txn_date', '>=', $start)
->whereDate('txn_date', '<=', $end)
->get();