Shopping Cart list problem: Collection was modified; enumeration operation may not execute.

Question

User-1671087770 posted

 I've created a ShoppingCart class that is a list of another class - cartItems. I want to be able to remove a cart item and I'm struggling a little with how to go about it correctly.

I've tried the following:

 

For Each item As CartItem In Profile.ShoppingCart.Items
            If item.ItemID = 11 Then
                Profile.ShoppingCart.Items.Remove(item)
            End If
        Next

 

But get this error:  Collection was modified; enumeration operation may not execute.

 

Is there a way round this. I want the user to be able to delete an item from their shopping cart.  (the shopping cart is stored as profile info)

 

Thanks in advance 

Answer 1

User1374904634 posted

 Hi,

you can't remove an item from a collection you're iterating with foreach. Beside that, removing an item from a collection you're iterating is dangerous, because if you don't write carefully the loop (for example, iterating backwards) you risk to get out of bounds.

My suggestion is: use a classic for loop. As soon as you find the item to remove, save the index to a variable and break from the loop. Then, pass the index to the RemoveAt method of the collection.
 

Answer 2

User-1671087770 posted

 Hi,

 Thanks for your suggested solution. I actually resolved this not long after I posted, but forgot to reply to myself. I checked whether I wanted to delete within the for loop, but didn't try and remove the item within the loop. Here's the code I used:

 

 

 Dim item2 As CartItem
        For Each item1 As CartItem In Profile.ShoppingCart.Items
            Dim TheID = item1.ItemID
            If item1.ItemID = ItemID Then
                item2 = item1
            End If
        Next
        If item2 IsNot Nothing Then
            Profile.ShoppingCart.Items.Remove(item2)
            Profile.Save()
        End If

 
Thanks for your help anyway.