I am creating a web app using .Net8 Blazor Server Side that can create a transaction and every transaction should deduct the balance.

What happened is that when I Add a Transaction:

private async void Submit()
{
    isVisible = true;
    await Task.Delay(1000);
    Transaction!.UserID = selectedUser?.id;
    Transaction!.DOCUMENT_NUM = DocumentNumber;
    Transaction.CREATED_DATE = DateValue;
    Transaction.PARTICULARS = Particulars;
    Transaction.AMOUNT = Amount;

    if (Amount > selectedUser!.Balance)
    {
        Snackbar.Add("User does not have enough balance.", Severity.Error);
        return;
    }
    Balance!.UserID = selectedUser?.id;
    Balance.Balance -= Amount;
    var tran = await tranService.AddTransactionAsync(Transaction);
    var bal = await balanceService.UpdateBalance(Balance);
    Snackbar.Add("Transaction added successfully", Severity.Success);
    await vwUserService.GetAllUsers();
    Transaction = new();
    selectedUser = new();
    await GenerateDocumentNumberAsync();
    Amount = 0;
    Particulars = string.Empty;
    users = new();
    users = await vwUserService.GetAllUsers();
    Balance = new();
    isVisible = false;
    StateHasChanged();
    return;
    
}

this will deduct the balance.

But in my Edit Transaction:

async Task UpdateTransaction()
{
    Transaction.ID = VwTransaction.ID;
    Transaction.CREATED_DATE = (DateTime)VwTransaction.CREATED_DATE;
    Transaction.DOCUMENT_NUM = VwTransaction.DOCUMENT_NUM;
    Transaction.UserID = VwTransaction.USERID;
    Transaction.PARTICULARS = VwTransaction.PARTICULARS;
    Transaction.AMOUNT = VwTransaction.AMOUNT;

    var updated = await tranService.UpdateTransaction(Transaction);
    if(updated is not null)
    {
        await Task.Delay(1000);
        Balance!.UserID = VwTransaction?.USERID;
        Balance.Balance -= Transaction.AMOUNT;
        await balanceService.UpdateBalance(Balance);
        Snackbar.Add("Transaction updated successfully", Severity.Success);
        return;
    }
    Snackbar.Add("Error Encountered", Severity.Error);
}

What I want to do is this:

1. Let’s say I have a balance of 5,000.00.
2. I added a transaction of 1,000.00.
3. So the balance should be 4,000.00, since 5,000.00 – 1,000.00 is 4,000.00.
4. But then I made a mistake in adding the transaction.
5. Instead of 1,000.00 the correct amount in adding the transaction should be 1,200.00.
6. So i try to edit the transaction and changed 1,000.00 to 1,200.00.
7. After editing the transaction, it should be 5,000.00 – 1,200.00 = 3,800.00

I am having trouble adding the 200.00 to the 1,000.00 and deducting the original balance and likewise, if I want to edit the added amount to something that is lower than 1,000.00 and deduct it to the original balance.

But with the code I have shown, it deducts twice. (1) when I add a transaction. (2) When I edit the transaction. The problem is in my Edit Transaction and I don’t know how to do it.