File picker multi select failed with selection of a lot of files.

Question

File picker multi select failed with selection of a lot of files.

Dani_S 4,501

Hi,

When i select 1000 files with multi select the app crash with this exception:

The maximum number of items for the access list has been reached. An item must be removed before another item is added. (0x80270220)

   PickOptions options = new()
   {
       //PickerTitle = "Please select files",
   };
   
   var fileResults = await _filePicker.PickMultipleAsync(options);

   public async Task<IEnumerable<FileResult>> PickMultipleAsync(PickOptions options)
   {
       try
       {
           var result = await FilePicker.Default.PickMultipleAsync(options);
           if (result != null)
           {
               return result;
           }
        }
        catch (Exception ex)
        {
           // The user canceled or something went wrong
        }

        return null;
   }

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This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.
Rob Caplan - MSFT 6,037 Reputation points Microsoft Employee Moderator

2023-05-09T22:53:01.3433333+00:00
I moved the second half of your code snippet into the main question. It's much easier to read (and therefore much easier to answer) if you put all relevant information in the main question. If you need to add technical details later you can edit it into the main question rather than adding it as a comment.

Also please make sure to include details about your environment, including:

The version of Maui that you're using. I'm assuming .Net 7 SR6, since that is currently the only supported version of Maui

The target platform and version that the error occurs in. From the error I assume this is Windows, but it's better to be explicit.

Any additional notes on the platform, such as if it's RTL and if you're building packaged or unpackaged. From previous posts I believe you're running RTL and unpackaged, but this error suggests that you're running packaged.

Essential details of the problem (well done in this post, but listing for completeness):

What are you trying to achieve

How are you trying to achieve it (minimal code snippet is good)

What is the actual behaviour

Include the text of any error messages

What is the expected behaviour

Accepted answer

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Your answer

Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.
Rob Caplan - MSFT 6,037 Reputation points Microsoft Employee Moderator

2023-05-09T22:53:01.3433333+00:00

I moved the second half of your code snippet into the main question. It's much easier to read (and therefore much easier to answer) if you put all relevant information in the main question. If you need to add technical details later you can edit it into the main question rather than adding it as a comment.

Also please make sure to include details about your environment, including:

The version of Maui that you're using. I'm assuming .Net 7 SR6, since that is currently the only supported version of Maui

The target platform and version that the error occurs in. From the error I assume this is Windows, but it's better to be explicit.

Any additional notes on the platform, such as if it's RTL and if you're building packaged or unpackaged. From previous posts I believe you're running RTL and unpackaged, but this error suggests that you're running packaged.

Essential details of the problem (well done in this post, but listing for completeness):

What are you trying to achieve

How are you trying to achieve it (minimal code snippet is good)

What is the actual behaviour

Include the text of any error messages

What is the expected behaviour

Answer 1

Rob Caplan - MSFT 6,037 Microsoft Employee Moderator

Assuming from the error that you're running in a packaged Windows app, the error is correct and descriptive. The FilePicker tries to add all picked files to the FutureAccessList, and the FutureAccessList can hold only 10000 items.

That said, there's no general need to add items to the FutureAccessList in a WinUI3 app as there was for a UWP app, so that's an unnecessary check. You can work around this by calling the Windows.Storage.Pickers.FileOpenPicker directly from platform specific code instead of calling the MAUI FilePicker. Here's a code snippet from the FileOpenPicker docs modified to initialize in a WinUI3 context and to demonstrate that the file can be opened from its Path, which doesn't carry the permissions granted by the FileOpenPicker.

#if WINDOWS
        FileOpenPicker openPicker = new FileOpenPicker();
        openPicker.ViewMode = PickerViewMode.Thumbnail;
        openPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
        openPicker.FileTypeFilter.Add(".jpg");
        openPicker.FileTypeFilter.Add(".jpeg");
        openPicker.FileTypeFilter.Add(".png");

        // HWND initialization needed for WinUI3
        var hwnd = WindowStateManager.Default.GetActiveWindow().GetWindowHandle();
        WinRT.Interop.InitializeWithWindow.Initialize(openPicker, hwnd);

        var files = await openPicker.PickMultipleFilesAsync();
        if (files != null)
        {
            foreach (var file in files)
            {
                // WinUI3 has full trust by default and so can open the Path with System.IO.File 
                // UWP would need to access this via the StorageFile
                using (FileStream f = System.IO.File.OpenRead(file.Path))
                {
                    Debug.WriteLine($"Picked photo: {file.Name} is {f.Length}");
                }
            }
        }
        else
        {
            Debug.WriteLine($"Operation cancelled.");
        }
#endif

Dani_S 4,501

1.I got exception:Error HRESULT E_FAIL has been returned from a call to a COM component.

2.The code:caller:

PickupFilesCommand = new Command(
                   execute: async () =>
                   {
                       
                       var fileResults = await _filePicker.PickMultipleAsync();
                       if (fileResults != null)
                       {
                           foreach (var fileResult in fileResults)
                           {
                               FilesNames += fileResult + ";" + Environment.NewLine;
                               Files.Add(new FileInfoData(new FileInfo(fileResult), Path.GetDirectoryName(fileResult)));
                            }
                       }

                   });

    public async Task<IEnumerable<string>> PickMultipleAsync()
        {
            List<string> results = new List<string>();

            try
            {
                FileOpenPicker openPicker = new FileOpenPicker();
               // openPicker.ViewMode = PickerViewMode.Thumbnail;

                // HWND initialization needed for WinUI3
                var hwnd = WindowStateManager.Default.GetActiveWindow().GetWindowHandle();
                WinRT.Interop.InitializeWithWindow.Initialize(openPicker, hwnd);

                 var files = await openPicker.PickMultipleFilesAsync();
                if (files != null)
                {
                    foreach (var file in files)
                    {
                        results.Add(file.Path);
                    }

                }
                
      
            }
            catch (Exception ex)
            {
                // The user canceled or something went wrong

            }
            return results; 
           

        }

3.I'm using net 6.

Dani_S 4,501 Reputation points

2023-05-10T06:56:22.8133333+00:00
I want end-user select the files.
Rob Caplan - MSFT 6,037 Reputation points Microsoft Employee Moderator

2023-05-10T17:43:22.27+00:00
If you look in the debug output window there should be a more explanatory message:

Exception thrown: 'System.Runtime.InteropServices.COMException' in WinRT.Runtime.dll WinRT information: The FileTypeFilters property must have at least one file type filter specified.

If you want to allow all file types then set the FileTypeFilters property to "*" as demonstrated in the FileTypePicker documentation. The ViewMode and SuggestedStartLocation are optional.:

FileOpenPicker openPicker = new FileOpenPicker(); openPicker.ViewMode = PickerViewMode.List; openPicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary; openPicker.FileTypeFilter.Add("*");

For more information on the Windows file picker see Open files and folders with a picker in the UWP documentation.

For more information on calling this from WinUI3 context (including Maui) see How to use FilePicker and FolderPicker in WinUI 3 and other desktop-based apps #1188 in the Windows App SDK repo.

Please note that some requirements were loosened in Windows 11. The sample code presented here should work in both and Windows 10 and 11.
Dani_S 4,501 Reputation points

2023-05-11T13:05:48.31+00:00

Thanks a lot.

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File picker multi select failed with selection of a lot of files.

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