list index out of range in Comparing two prices

Question

I want to compare the received price with the previous prices and send a message if it was lower, but it shows this error to receive the first entry. I also tried to try and while. It didn't give the expected result.

If I remove this condition and enter a number and apply this condition again. The code works correctly.

IndexError at /bid/2/
list index out of range
File "C:\Users\N\Desktop\my own\views.py", line 98, in bid
elif bid_price <= other_off[0].bid_price :

def bid(request, bidid):                                                                                                                                                                          
    bid_price = Decimal(request.POST.get('bid_price', False))
    other_off = 
    Bid_info.objects.filter(product=product).order_by('- 
    bid_price')
    
    if Bid_info.objects.filter(product=product, 
                                   seller=request.user).exists():
        messages.warning(request, "You've already made an offer 
                                   for this product.")
    elif bid_price <= other_off[0].bid_price :
        messages.warning(request, "Your offer must be greater 
                                   than other offers.")
   else:
        Bid_ = Bid_info(product=product, seller=request.user, bid_price=bid_price)

Answer 1

There are no Bids for that Product, hence other_off[0] will not work. You can however first check if there is a bit, and do this all in the same query with:

def bid(request, bidid):
    bid_price = Decimal(request.POST.get('bid_price', False))
    other_off = (
        Bid_info.objects.filter(product=product).order_by('-bid_price').first()
    )

    if Bid_info.objects.filter(product=product, seller=request.user).exists():
        messages.warning(
            request, "You've already made an offer for this product."
        )
    elif other_off and bid_price <= other_off.bid_price:
        messages.warning(request, "Your offer must be greater than other offers.")
    else:
        Bid_ = Bid_info.objects.create(
            product=product, seller=request.user, bid_price=bid_price
        )