Upload/Download file from Sharepoint using AD Authentication

To upload and download files from SharePoint using AD authentication in a .NET Web API, you can utilize the SharePoint Client Object Model (CSOM). Below is a concise example demonstrating both operations.

Uploading a File

using Microsoft.SharePoint.Client;

public void UploadFile(string siteUrl, string filePath, string targetFolder)
{
    var securePassword = new SecureString();
    foreach (char c in "your_password") securePassword.AppendChar(c);
    
    using (var context = new ClientContext(siteUrl))
    {
        context.Credentials = new NetworkCredential("your_username", securePassword, "your_domain");
        var targetList = context.Web.Lists.GetByTitle("Documents");
        var fileCreationInfo = new FileCreationInformation
        {
            Content = System.IO.File.ReadAllBytes(filePath),
            Url = Path.GetFileName(filePath),
            Overwrite = true
        };
        var uploadFile = targetList.RootFolder.Files.Add(fileCreationInfo);
        context.ExecuteQuery();
    }
}

Downloading a File

public void DownloadFile(string siteUrl, string fileUrl, string downloadPath)
{
    var securePassword = new SecureString();
    foreach (char c in "your_password") securePassword.AppendChar(c);
    
    using (var context = new ClientContext(siteUrl))
    {
        context.Credentials = new NetworkCredential("your_username", securePassword, "your_domain");
        var fileInfo = File.OpenBinaryDirect(context, fileUrl);
        using (var fileStream = new FileStream(downloadPath, FileMode.Create))
        {
            fileInfo.Stream.CopyTo(fileStream);
        }
    }
}

Ensure you replace placeholders like your_username, your_password, and your_domain with actual values. This approach allows seamless interaction with SharePoint while leveraging AD authentication for secure access.