(401) Unauthorized exception while downloading file from SharePoint
After trying a lot of alternatives, I have come to conclusion that OpenBinaryDirect() cannot be used with OAuth tokens. I was able to download file from SharePoint Online using two other approaches. I am posting the answers here so that it might help someone:
Approach 1 (OpenBinaryStream):
var file = clientContext.Web.GetFileByServerRelativeUrl(fileRef);
clientContext.Load(file);
clientContext.ExecuteQuery();
ClientResult<Stream> streamResult = file.OpenBinaryStream();
clientContext.ExecuteQuery();
While this approach works perfectly, OpenBinaryStream
is not available in Microsoft.SharePoint.Client.dll
<= v 14.0.0.0.
Approach 2 (WebClient or Other Http Requests):
string downloadUrl = HostURL + "/_api/web/getfilebyserverrelativeurl('" + fileRef + "')/$value";
WebClient client = new WebClient();
client.Headers.Add("Authorization", "Bearer " + accessToken);
client.DownloadFile(downloadUrl, filePath);
Note the download URL that I have used for WebClient. Normal file URL will not work to download files from SharePoint Online.