Uploading Files to Sharepoint using Microsoft Graph API - C#

In this blog post, we will explore how to upload files to a SharePoint folder using the Microsoft Graph API. If you haven’t already, make sure to refer to my previous article on authentication to set up your authentication with Microsoft Graph.

Once you have your authentication in place, follow the steps below to upload files to SharePoint.

Step 1: Get the Drive ID

The first step in uploading a file is to get the Drive ID associated with your SharePoint site and list.

private async Task<string> GetDriveId(string siteId, string listId)
{
    Drive listDrive = await _graphClient.Sites[siteId]
                                        .Lists[listId]
                                        .Drive
                                        .GetAsync();
    if (listDrive == null)
    {
        _logger($"Unable to get drive with siteId: {siteId} and listId: {listId}", EventLogEntryType.Error);
        return string.Empty;
    }
    return listDrive.Id;
}

Step 2: Get or Create the Folder by Name

Next, you need to get the folder by name or create it if it doesn’t exist.

private async Task<DriveItem> GetFolderByFolderName(string driveId, string folderName)
{
    DriveItemCollectionResponse folderSearch = null;
    folderSearch = await _graphClient.Drives[driveId]
                                     .Items
                                     .GetAsync(requestConfig => requestConfig.QueryParameters.Filter = $"Name eq '{folderName}'");

    bool folderIsNull = folderSearch == null || folderSearch.Value == null || folderSearch.Value.Count == 0;
    if (!folderIsNull)
        folder = folderSearch.Value[0];

    if (folderIsNull)
    {
        DriveItem newFolderDriveItemPostRequest = new DriveItem
        {
            Name = folderName,
            Folder = new Folder { },
            AdditionalData = new Dictionary<string, object>
            {
                {
                    "@microsoft.graph.conflictBehavior" , "fail"
                },
            },
        };
        DriveItem newFolderDriveItem = null;
        newFolderDriveItem = await _graphClient.Drives[driveId]
                                               .Items
                                               .PostAsync(newFolderDriveItemPostRequest);
        if (newFolderDriveItem != null)
        {
            folder = newFolderDriveItem;
            _logger($"Successful folder creation. folderName: {folderName}, folderId: {newFolderDriveItem.Id}", EventLogEntryType.Information);
        }
    }

    return folder;
}

Step 3: Upload the File to the Folder

Finally, upload your file to the specified folder. This method handles both small and large files using an upload session.

private async Task UploadFileToFolder(string filePath, string driveId, string folderId)
{
    using (Stream fileStream = File.OpenRead(filePath))
    {
        CreateUploadSessionPostRequestBody uploadSessionRequestBody = new CreateUploadSessionPostRequestBody
        {
            Item = new DriveItemUploadableProperties
            {
                AdditionalData = new Dictionary<string, object>
                {
                    { "@microsoft.graph.conflictBehavior", "rename" }, // fail, replace, or rename
                },
            },
        };
        UploadSession uploadSession = await _graphClient.Drives[driveId]
                                                        .Items[folderId]
                                                        .ItemWithPath(Path.GetFileName(filePath))
                                                        .CreateUploadSession
                                                        .PostAsync(uploadSessionRequestBody);

        int maxSliceSize = 320 * 1024;
        LargeFileUploadTask<DriveItem> fileUploadTask = new LargeFileUploadTask<DriveItem>(uploadSession, fileStream, maxSliceSize, _graphClient.RequestAdapter);

        long totalLength = fileStream.Length;
        IProgress<long> progress = new Progress<long>(prog => Console.WriteLine($"Uploaded {prog} bytes of {totalLength} bytes"));

        try
        {
            UploadResult<DriveItem> uploadResult = await fileUploadTask.UploadAsync(progress);
            _logger($"Successful file upload. filePath: {filePath}. folderId: {folderId}", EventLogEntryType.Information);
        }
        catch (ODataError ex)
        {
            _logger($"Error uploading. filePath: {filePath}. folderId: {folderId}:\n{ex.Error?.Message}", EventLogEntryType.Error);
        }
    }
}

By following these steps, you can upload files to a SharePoint folder using the Microsoft Graph API.