I am attempting to enumerate the values in a listview and seem to be receiving an error.

Question

1.00/5 (1 vote)

See more:

The listview is created like this when the app loads:

ListView1.Items.Add(new Folders() { pth = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile) + "\\" + "Desktop" });
ListView1.Items.Add(new Folders() { pth = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile) + "\\" + "Documents" });
ListView1.Items.Add(new Folders() { pth = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile) + "\\" + "Downloads" });
ListView1.Items.Add(new Folders() { pth = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile) + "\\" + "Music" });
ListView1.Items.Add(new Folders() { pth = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile) + "\\" + "Pictures" });
ListView1.Items.Add(new Folders() { pth = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile) + "\\" + "Videos" });

The code I am using to enumerate it is as follows:

int column = 1;
 foreach (System.Windows.Forms.ListViewItem item in ListView1.Items)
 {
     string source = item.SubItems[column].Text;
     MessageBox.Show(source);
 }

The error I receive when I click the button is as follows:

System.InvalidCastException
  HResult=0x80004002
  Message=Unable to cast object of type 'Folders' to type 'System.Windows.Forms.ListViewItem'.
  Source=Backup Tool
  StackTrace:
   at Backup_Tool.MainWindow.FldBackup_Click(Object sender, RoutedEventArgs e) in C:\Users\brian\source\repos\Backup Tool\Backup Tool\MainWindow.xaml.cs:line 95
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.UIElement.RaiseEvent(RoutedEventArgs e)
   at System.Windows.Controls.Primitives.ButtonBase.OnClick()
   at System.Windows.Controls.Button.OnClick()
   at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e)
   at System.Windows.UIElement.OnMouseLeftButtonUpThunk(Object sender, MouseButtonEventArgs e)
   at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent)
   at System.Windows.UIElement.OnMouseUpThunk(Object sender, MouseButtonEventArgs e)
   at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
   at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
   at System.Windows.Input.InputManager.ProcessStagingArea()
   at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
   at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
   at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
   at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)
   at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
   at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
   at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
   at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
   at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
   at System.Windows.Application.RunDispatcher(Object ignore)
   at System.Windows.Application.RunInternal(Window window)
   at System.Windows.Application.Run(Window window)
   at System.Windows.Application.Run()
   at Backup_Tool.App.Main()

What on earth am I doing wrong? I hope someone can help. I am using Visual Studios 2019 creating a WPF Grid app.

What I have tried:

I have tried enumerating as a string in various ways but nada... Suggestions?

Posted 24-Mar-20 10:33am

bjwaldo

Updated 25-Mar-20 2:10am

Add a Solution

3 solutions

Solution 2

You should use the full enumeration name for the folders you want, as listed at Environment.SpecialFolder Enum (System) | Microsoft Docs[^]. That way you get the full path as a string which you can insert straight into the ListView.

Posted 24-Mar-20 23:24pm

Richard MacCutchan

Solution 1

That's because your ListView item collection is of type Folders which you are casting to ListViewItem. Try following way

foreach (Folders item in ListView1.Items)
{
    //string source = item.SubItems[column].Text; //this would now be "pth" property
    MessageBox.Show(source);
}

Posted 24-Mar-20 16:27pm

AnkushK1

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

phil.o · Accepted Answer · 2020-03-25T02:11:00

First, you should use built-in way of getting users folders, as suggested in solution 2:

C#

ListView1.Items.Add(new Folders() { pth = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory) });
ListView1.Items.Add(new Folders() { pth = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) });
ListView1.Items.Add(new Folders() { pth = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), "Downloads") });
ListView1.Items.Add(new Folders() { pth = Environment.GetFolderPath(Environment.SpecialFolder.MyMusic) });
ListView1.Items.Add(new Folders() { pth = Environment.GetFolderPath(Environment.SpecialFolder.MyPictures) });
ListView1.Items.Add(new Folders() { pth = Environment.GetFolderPath(Environment.SpecialFolder.MyVideos) });

Note preferred usage of Path.Combine Method (System.IO) | Microsoft Docs[^] to build path instead of using string concatenations.

Then you can enumerate the items this way:

C#

foreach (Folders item in ListView1.Items.Cast<Folders>())
{
     string source = item.pth;
     MessageBox.Show(source);
}