CODEWITHSUNDEEP
c#uwp
Reaperino
Reaperino

Reputation: 145

Unable to read a file in FutureAccessList

I'm trying to read a CSV file chosen with a OpenFilePicker and put into the FutureAccessList. But whenever I try to read it I get an DeniedAccessException.

That function is a test :

private async Task readCSVCustomAsync()
{
    ApplicationDataContainer localSettings = ApplicationData.Current.LocalSettings;
    StorageFile file;
    FileOpenPicker openPicker = new FileOpenPicker();
    openPicker.SuggestedStartLocation = PickerLocationId.Desktop;
    openPicker.FileTypeFilter.Add("*");
    //picking a file with FilePicker
    file = await openPicker.PickSingleFileAsync();
    //Storing file in futureaccesslist
    string faToken = StorageApplicationPermissions.FutureAccessList.Add(file);

    //getting the file from FA list
    var fileOpenTest = await StorageApplicationPermissions.FutureAccessList.GetFileAsync(faToken);

    //trying to read it
    using (var reader = new StreamReader(fileOpenTest.Path)) //Exception here
    using (var csv = new CsvReader(reader))
    {
        //elimination des premieres lignes avant le header
        bool headerOK = false;
        while (csv.Read() && !headerOK)
        {
            string rec = csv.GetField(0) + csv.GetField(1);
            if (!rec.Equals(""))
            {
                csv.ReadHeader();
                headerOK = true;
            }
        }
    }
}

So here I'm trying to put the file in the FA List and retrieve it later to read the content (it's a csv file that I picked).

But even if I put it in the FutureAccessList I get an AccessDeniedException when I'm trying to read it, why I am getting that exception ?

Upvotes: 0

Views: 66

Answers (1)

Nico Zhu
Nico Zhu

Reputation: 32785

Unable to read a file in FutureAccessList

The problem is you could not use System.IO.StreamReader to access file where in the FutureAccessList with path, and the path property only available in the Windows Storage API. So you need to open the file as steam, then invoke this var reader = new StreamReader(stream).

private async Task readCSVCustomAsync()
{
    ApplicationDataContainer localSettings = ApplicationData.Current.LocalSettings;
    StorageFile file;
    FileOpenPicker openPicker = new FileOpenPicker();
    openPicker.SuggestedStartLocation = PickerLocationId.Desktop;
    openPicker.FileTypeFilter.Add("*");
    //picking a file with FilePicker
    file = await openPicker.PickSingleFileAsync();
    //Storing file in futureaccesslist
    string faToken = StorageApplicationPermissions.FutureAccessList.Add(file);

    //getting the file from FA list
    var fileOpenTest = await StorageApplicationPermissions.FutureAccessList.GetFileAsync(faToken);
     // open file as stream, to avoid using path property
    var stream = await fileOpenTest.OpenStreamForReadAsync();
    //trying to read it
    using (var reader = new StreamReader(stream)) 
    using (var csv = new CsvReader(reader))
    {
        //elimination des premieres lignes avant le header
        bool headerOK = false;
        while (csv.Read() && !headerOK)
        {
            string rec = csv.GetField(0) + csv.GetField(1);
            if (!rec.Equals(""))
            {
                csv.ReadHeader();
                headerOK = true;
            }
        }
    }
}

Upvotes: 1

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