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I have a table named bills. in the table one field is amount and another field is bill_amount_left. I want to sum up the bill_amount_left when a new bill is added. If a bill is created against an user then, users previous bill_amount_left will be automatically increased with the new bill. How to do that?
$data = $this->validate([
'property_id' => 'required',
'amount' => 'required',
'due_date' => 'required',
'start_date' => 'required',
'end_date' => 'required',
'bill_type' => 'required',
'remark' => 'required',
]);
$data['amount_left'] = $data['amount'];
$bill = Bill::create($data);
I am using these code to create a bill. So, I need to update the amount_left field every time a new bill is created. Also I need to identify against which property they bill is created. For example a bill is created against property_id 1. Then another bill created against property_id 1. So the field amount_left should automatically increased with newly created bill.
@ash92 if I understand the question correctly, you can create observer https://laravel.com/docs/9.x/eloquent#observers and watch creating event
public function creating(Bill $bill)
{
if ($previousBill = Bill::where('property_id', $bill->property_id)->latest('id')->first()) {
$bill->bill_amount_left = $previousBill->bill_amount_left + $bill->amount;
}
}
@SilenceBringer Thanks for your reply. Your code worked. But I wanted to do like update previous record also. For example I have a bill for property1 previously 1000$. Now I will add another bill against same property and bill_amount_left field of record one also needed to update. Is it possible ? or it is best practice to update latest record and keep old one as it is for future reference? Thank you again.
@Ash92 hmm... add created event
public function creating(Bill $bill)
{
if ($previousBill = Bill::where('property_id', $bill->property_id)->latest('id')->first()) {
$bill->bill_amount_left = $previousBill->bill_amount_left + $bill->amount;
}
}
public function created(Bill $bill)
{
Bill::where('property_id', $bill->property_id)->update('bill_amount_left ', $bill->bill_amount_left );
}
@SilenceBringer SQLSTATE[42S22]: Column not found: 1054 Unknown column '0' in 'field list' this is the error if i use the code.
@Ash92 Oops
public function created(Bill $bill)
{
Bill::where('property_id', $bill->property_id)->update(['bill_amount_left' => $bill->bill_amount_left]);
}
I don't understand, where/how is defined $previousBill ?
Writing php (laravel) code to do cumulative sum will conduct you to write some code to check for no error due to events mangement.
You can do it in a more robust way directly in the db
https://popsql.com/learn-sql/mysql/how-to-calculate-cumulative-sum-running-total-in-mysql
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