How to enable DocumentsLibrary capability in a Win

问题:

I just created a new blank XAML/C# Windows Store app in Visual Studio. I tried to create a file in the Documents folder with this code:

// DEBUG ONLY:
StorageFile file = await KnownFolders.DocumentsLibrary.CreateFileAsync("Hey lol.txt");

But it throws this exception (which I expected):

WinRT information: Access to the specified location (DocumentsLibrary) requires a capability to be declared in the manifest.

Which is fine. I expected it. So I go to Package.appxmanifest and go to Capabilities tab, and to my surprise, there is no "DocumentsLibrary" capability listed.

How do I enable it if it's not even there?

回答1:

Looks like your answer is here. The author shows it available in VS2012, but gone from the list in VS2013, citing MS policy against accessing that particular folder.

[Although] this capability is gone just from the UI, you still can open appxmanifest source and manually add the capability. The result will probably be the same as before – failure of certification for individual developers, so you better stay away from this trick. Microsoft strongly recommend against using Documents Library capability, suggesting Folder and File Pickers instead.

回答2:

As per Grant's answer, a way around this is to add the Capability manually.

Right-click the Package.appxmanifest file in Solution Explorer, and select "View code", then either find the Capabilities element, or add it yourself:

...
  <Capabilities>
    <Capability Name="internetClient" />
    <Capability Name="removableStorage" />
    <Capability Name="documentsLibrary" />
  </Capabilities>
</Package>

回答3:

Here's what you'll get from the Windows Store when you try to publish it

回答4:

As this is UAP the syntax needs to state this, should be as followed

  <Capabilities>
    <Capability Name="internetClient" />
    <uap:Capability Name="documentsLibrary" />
  </Capabilities>

You need to add 'uap:' in front of Capability