Find selected WPF Listbox entries

Question

I've been trying iterate through the selected items of a listbox in WPF, with the following code;

        try
        {
            for (int i = 0; i < mylistbox.SelectedItems.Count; i++)
            {
                ListItem li = (ListItem)mylistbox.SelectedItems[i];

                string listitemcontents_str = li.ToString();
            }
        }
        catch(Exception e)
        {
            // Error appears here
            string error = e.ToString();
        }

However I receive an invalid cast exception;

System.InvalidCastException: Unable to cast object of type 'mylist' to type 'System.Windows.Documents.ListItem'.

Is there a way around this?

Answer 1

This should work:

       for (int i = 0; i < mylistbox.SelectedItems.Count; i++)
        {
            var li = mylistbox.SelectedItems[i];

            string listitemcontents_str = li.ToString();
        }

Answer 2

I prefer to do it using data binding: http://stackoverflow.com/questions/1297643/sync-selecteditems-in-a-muliselect-listbox-with-a-collection-in-viewmodel/1299544#1299544

Answer 3

  for (int i = 0; i < mylistbox.SelectedItems.Count; i++)
    {
        List**Box**Item li = (List**Box**Item)mylistbox.SelectedItems[i];

        string listitemcontents_str = li.ToString();
    }

Answer 4

The listbox adds it's items as a collection of objects, so it can't cast it to ListItem. So for your purpose , you can do as following :

for (int i = 0; i < mylistbox.SelectedItems.Count; i++) 
        {           

            string listitemcontents_str = mylistbox.SelectedItems[i].ToString(); 
        } 

If you really want to use ListBoxItem , please add these items to your listbox e.g.

ListBoxItem li = new ListBoxItem();
li.Content = "Hello";
mylistbox.Items.Add(li);

then you can do what you want without Invalid cast exception:

for (int i = 0; i < mylistbox.SelectedItems.Count; i++)
            {
            ListBoxItem li = (ListBoxItem)mylistbox.SelectedItems[i];
            string s = li.ToString();
            }

Answer 5

A way I found was to assign the listbox onto an object then cast this onto a DataRowView. Seems to work and I can get access to the fields inside, by their respective column names.

object selected = mylistbox.SelectedItem; DataRow row = ((DataRowView)selected).Row;
string thecontents = row["columnname"].ToString().TrimEnd();

Answer 6

You are confusing ListItem with ListBoxItem.

If you do nothing special, a ListBox will create ListBoxItem containers for the data you bind to it. ListItem is used inside FlowDocument and is basically a numbered or bulleted point in a document.

That said, data binding would be better. If you were using data binding, SelectedItems would not be a ListBoxItem but would be your actual data item that was bound. You can cast this to the appropriate type and use it.