使用MS Graph SDK从共享的OneDrive文件夹下载并上传DriveItem

Question

I'm currently trying to implement several tasks that involve listing, uploading and downloading files from a shared OneDrive folder. This folder is accesible via the logged in users OneDrive (visible in his root folder). The listing part works pretty well so far, using this code:

string remoteDriveId = string.Empty;
private GraphServiceClient graphClient { get; set; }
// Get the root of the owners OneDrive
DriveItem ownerRoot = await this.graphClient.Drive.Root.Request().Expand("thumbnails,children($expand=thumbnails)").GetAsync();
// Select the shared folders general information
DriveItem sharedFolder = ownerRoot.Children.Where(c => c.Name == "sharedFolder").FirstOrDefault();

// Check if it is a remote folder
if(sharedFolder.Remote != null)
{
    remoteDriveId = item.RemoteItem.ParentReference.DriveId;

    // Get complete Information of the shared folder
    sharedFolder = await graphClient.Drives[remoteDriveId].Items[sharedFolder.RemoteItem.Id].Request().Expand("thumbnails,children").GetAsync();
}

So obviously I need to retrieve the shared folders information from the OneDrive that shared it with the other OneDrive. Next part for me is to list the contents of this shared folder, which also works pretty well like this:

foreach (DriveItem child in sharedFolder.Children)
{
    DriveItem childItem = await graphClient.Drives[remoteDriveId].Items[child.Id].Request().Expand("thumbnails,children").GetAsync();

    if(childItem.Folder == null)
    {
         string path = Path.GetTempPath() + Guid.NewGuid();
         // Download child item to path
    }
}

My problem starts with the "Download child item to path" part. There I want to download everything, that is not a folder to a temporary file. The problem is that OneDrive always answers my request with an error message, that the file was not found. What I tried so far is:

using (var stream = await graphClient.Drives[remoteDriveId].Items[childItem.Id].Content.Request().GetAsync())
using (var outputStream = new System.IO.FileStream(path, System.IO.FileMode.Create))
{
    await stream.CopyToAsync(outputStream);
}

In another variant I tried to use the ID of the childItem ParentReference (but I think this will only lead me to the remote OneDrives ID of sharedFolder):

using (var stream = await graphClient.Drives[remoteDriveId].Items[childItem.ParentReference.Id].Content.Request().GetAsync())
using (var outputStream = new System.IO.FileStream(path, System.IO.FileMode.Create))
{
    await stream.CopyToAsync(outputStream);
}

After Downloading the files I want to edit them and reupload them to a different path in the shared folder. That path is created by me (which allready works) like this:

DriveItem folderToCreate = new DriveItem { Name = "folderName", Folder = new Folder() };
await graphClient.Drives[remoteDriveId].Items[sharedFolder.Id].Children.Request().AddAsync(folderToCreate);

The upload then fails. I've tried it like this:

using (var stream = new System.IO.FileStream(@"C:\temp\testfile.txt", System.IO.FileMode.Open))
{
    await graphClient.Drives[remoteDriveId].Items[sharedFolder.Id].Content.Request().PutAsync<DriveItem>(stream);
}

And also like this (which works if it is not a shared folder and I therefore use Drive instead of Drives ):

using (var stream = new System.IO.FileStream(@"C:\temp\testfile.txt", System.IO.FileMode.Open))
{
    string folderPath = sharedFolder.ParentReference == null ? "" : sharedFolder.ParentReference.Path.Remove(0, 12) + "/" + Uri.EscapeUriString(sharedFolder.Name);
    var uploadPath = folderPath + "/" + uploadFileName;
    await graphClient.Drives[remoteDriveId].Root.ItemWithPath(uploadPath).Content.Request().PutAsync<DriveItem>(stream);
}

I couldn't get the AddAsync method (like in the folder creation) to work because I don't know how to create a DriveItem from a Stream .

If somebody could point me in the right direction I would highly appreciate that! Thank you!

Answer 1

The request:

graphClient.Drives[remoteDriveId].Items[childItem.ParentReference.Id].Content.Request().GetAsync()

corresponds to Download the contents of a DriveItem endpoint and is only valid if childItem.ParentReference.Id refers to a File resource , in another cases it fails with expected exception:

Microsoft.Graph.ServiceException: Code: itemNotFound Message: You cannot get content for a folder

So, to download content from a folder the solution would be to:

• enumerate items under folder: GET /drives/{drive-id}/items/{folderItem-id}/children
• per every item explicitly download its content if driveItem corresponds to a File facet: GET /drives/{drive-id}/items/{fileItem-id}/content

Example

var sharedItem = await graphClient.Drives[driveId].Items[folderItemId].Request().Expand(i => i.Children).GetAsync();
foreach (var item in sharedItem.Children)
{
    if (item.File != null)
    {
        var fileContent = await graphClient.Drives[item.ParentReference.DriveId].Items[item.Id].Content.Request()
                    .GetAsync();
        using (var fileStream = new FileStream(item.Name, FileMode.Create, System.IO.FileAccess.Write))
           fileContent.CopyTo(fileStream);

    }
}

Example 2

The example demonstrates how to download file from a source folder and upload it into a target folder:

  var sourceDriveId = "--source drive id goes here--";
  var sourceItemFolderId = "--source folder id goes here--";
  var targetDriveId = "--target drive id goes here--";
  var targetItemFolderId = "--target folder id goes here--";

 var sourceFolder = await graphClient.Drives[sourceDriveId].Items[sourceItemFolderId].Request().Expand(i => i.Children).GetAsync();
 foreach (var item in sourceFolder.Children)
 {
    if (item.File != null)
    {
        //1. download a file as a stream
        var fileContent = await graphClient.Drives[item.ParentReference.DriveId].Items[item.Id].Content.Request()
            .GetAsync();
        //save it into file 
        //using (var fileStream = new FileStream(item.Name, FileMode.Create, System.IO.FileAccess.Write))
        //    fileContent.CopyTo(fileStream);


        //2.Upload file into target folder
        await graphClient.Drives[targetDriveId]
             .Items[targetItemFolderId]
             .ItemWithPath(item.Name)
             .Content
             .Request()
             .PutAsync<DriveItem>(fileContent);

    }
 }

---

Instead of downloading/uploading file content, i think what you are actually after is DriveItem copy or move operations. Lets say there are files that needs to be copied from one ( source ) folder into another ( target ), then the following example demonstrates how to accomplish it:

  var sourceDriveId = "--source drive id goes here--";
  var sourceItemFolderId = "--source folder id goes here--";
  var targetDriveId = "--target drive id goes here--";
  var targetItemFolderId = "--target folder id goes here--";

  var sourceFolder = await graphClient.Drives[sourceDriveId].Items[sourceItemFolderId].Request().Expand(i => i.Children).GetAsync();
  foreach (var item in sourceFolder.Children)
  {
      if (item.File != null)
      {
          var parentReference = new ItemReference
          {
               DriveId = targetDriveId,
               Id = targetItemFolderId
          };
          await graphClient.Drives[sourceDriveId].Items[item.Id]
              .Copy(item.Name, parentReference)
              .Request()
              .PostAsync();
         }
      }
  }