Question

I am trying to get the first and last values in a list. The query operator First() is supported but Last() and LastOrDefault() give an error. Am I using the Last() operator incorrectly?

var purchaseBills = db.PurchaseBills.OrderBy(p => p.BillID);

if (purchaseBills.Count() >0)
{
    var firstBill = purchaseBills.First(); // This is supported

    // Attempt 1                    
    var lastBill = purchaseBills.Last(); // Not supported
    
    // Attempt 2
    var lastBill = purchaseBills.LastOrDefault(); // Not supported

    //Attempt 3
    var lastBill = purchaseBills.Reverse().First(); // Not supported
    
    textBoxPurchaseBillFrom.Text = firstBill.BillNo.ToString();
    textBoxPurchaseBillTo.Text = lastBill.BillNo.ToString();
}

Update:

–Errors–

Attempt 1: The query operator ‘Last‘ is not supported.

Attempt 2: The query operator ‘LastOrDefault‘ is not supported.

Attempt 3: The query operator ‘Reverse‘ is not supported.

Answer 1

• Instead of putting it into an own list by calling ToList() or ToArray() i would prefer to use AsEnumerable().
• Additionally like the others you should try OrderByDescending()
• Instead of Count() i would use Any().