ListBox SelectionMode Single multiple select

2
votes

I'm having a rather strange problem while working with a ListBox on a WPF program. I've defined my ListBox SelectionMode as Single, but it appear that even if visually I cannot select multiples items, it happens in the code. As can be seen here : SelectionModeSingleWithMultipleSelected

When trying to do a workaround, I tried to use the function UnselectAll, it rather strangly still leave an item selected : UnselectAllStillSelected

And as a last gift, once multiple items have been selected, if I try to click on my unselected visualy, selected in the code, item my application crash with a System.ArgumentException (I suppose it tries to select my item, that's already selected in fact, so it crashes because of adding a perfect duplicate ?) ApplicationCrashOnListBoxClick

I looked into ListBox is selecting many items even in SelectionMode="Single" that had kindof the same problem, but in my case I cannot visually select multiples items, and my items are completly distinct so it doesn't really help.

I don't have any custom behavior on ListBox.Click that could mess with something ...

my ListBox.ItemsSource is bound to a list of Items. I will decrement the value of a property of the selected Item when calling useItem on it, but it is still the same item (I don't recreate it/remove it then add it again)

Where is my problem coming from ? How can I fix it ?

2
c#wpflistboxlistboxitem
Is SelectedItems bound to anything in your xaml? – HasaniH
is it possible that something else is adding items to that list? – HasaniH
I'm modifying the selected item in the 'useItem' function (my item posses an int charge field that I decrease by 1). But I only modify the item, I do not create a new one. – Belterius

2 Answers

5
votes

So, finally found the origin of my problem.

Having a custom Item, I had to redefine my Equals function. I then had to redefine my GetHashCode function too, which I based on several of my properties, including the field I am decrementing ...
So when I would change the field, I would at the same time change my HashCode and I couldn't access my item anymore.

Changing my GetHashCode function to base it on an immutable field solved my problem.

1
votes

If your SelectionMode is Single, you should not bind to SelectedItems as per documentation. Just use SelectedItem.