Sharepoint 2013 REST API call using C#

Question

This is a follow-up question to one of my earlier question in Stackoverflow.

I am trying to connect to Sharepoint Online Premise to get documents in the "Document Library" by using the HTTPClient and the Sharepoint 2013 REST API.

All i am doing here is a Simple Anonymous HTTP GET call using HttpClient.

The code is as follows :

System.Net.Http.HttpClient _Client = new System.Net.Http.HttpClient();
_Client.BaseAddress = new Uri("https://test.sharepoint.com/_vti_bin/ListData.svc");
_Client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/atom+xml"));
_Client.DefaultRequestHeaders.Add("auth_user", "[email protected]");
_Client.DefaultRequestHeaders.Add("auth_pass", "test");
_Client.DefaultRequestHeaders.Add("Accept", "application/json;odata=verbose");
HttpResponseMessage resp = _Client.GetAsync(new Uri("https://test.sharepoint.com/_vti_bin/ListData.svc/Documents()")).Result;
string respString = resp.Content.ReadAsStringAsync().Result;

And i am getting the following error:

Unable to read data from the transport connection: The connection was closed.

Stack Trace is as follows :

[IOException: Unable to read data from the transport connection: The connection was closed.]
   System.Net.ConnectStream.EndRead(IAsyncResult asyncResult) +6501654
   System.Net.Http.WebExceptionWrapperStream.EndRead(IAsyncResult asyncResult) +30
   System.Net.Http.StreamToStreamCopy.BufferReadCallback(IAsyncResult ar) +54

[HttpRequestException: Error while copying content to a stream.]

[AggregateException: One or more errors occurred.]
   System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions) +3569193
   System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification) +73
   System.Threading.Tasks.Task`1.get_Result() +10522673
   WebApp.Test.Page_Load(Object sender, EventArgs e) in @Location
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +51
   System.Web.UI.Control.OnLoad(EventArgs e) +92
   System.Web.UI.Control.LoadRecursive() +54
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +772

I have gone through various blogs/articles to get some idea to solve the issue.But i cudn't find any solution yet.

Any thoughts on this?

Answer 1

This will help you:

ServicePointManager.ServerCertificateValidationCallback = 
    delegate(object s, X509Certificate certificate, X509Chain chain, 
            SslPolicyErrors sslPolicyErrors) 
    { 
        return true; 
    };

Put it before request.

Answer 2

I put together a quick .NET 4.5 console app in Visual Studio 2013 and was able to get your code working with a few minor changes and am able to successfully authenticate and call SharePoint Online's REST API.

Change #1: I added project references to the two SharePoint 2013 Client-Side Object Model (CSOM) DLLs. You can install the DLLs from here: http://www.microsoft.com/en-us/download/details.aspx?id=35585. Run the installer and add project references to Microsoft.SharePoint.Client.dll and Microsoft.SharePoint.Client.Runtime.dll. The reason you need those is so you can use the SharePointOnlineCredentials class.

Change #2: I added the "await" keyword to your two async calls because the code wasn't actually waiting for those calls to execute.

Change #3: I modified the HttpClient code to (1) use credentials from the SharePointOnlineCredentials object, (2) Get and use an authentication cookie from SharePoint Online, and (3) add one additional request header that's needed.

Here's the complete code snippet:

Uri uri = new Uri("https://mydomain.sharepoint.com");

SharePointOnlineCredentials creds = new SharePointOnlineCredentials(
    "[email protected]", StringUtilities.ToSecureString("YourPassword"));

string authCookie = creds.GetAuthenticationCookie(uri);
var cookies = new CookieContainer();
cookies.Add(new Cookie("FedAuth", authCookie.TrimStart("SPOIDCRL=".ToCharArray()), "", uri.Authority));

System.Net.Http.HttpClientHandler handler = new System.Net.Http.HttpClientHandler()
{
    Credentials = creds,
    CookieContainer = cookies
};

System.Net.Http.HttpClient client = new System.Net.Http.HttpClient(handler);

client.BaseAddress = new Uri(uri, "/_vti_bin/ListData.svc");
client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/atom+xml"));
client.DefaultRequestHeaders.Add("Accept", "application/json;odata=verbose");
client.DefaultRequestHeaders.Add("X-FORMS_BASED_AUTH_ACCEPTED", "f");

var response = await client.GetAsync(new Uri(uri, "/_vti_bin/ListData.svc/Documents()"));
string text = await response.Content.ReadAsStringAsync();

I ran this and printed out the "text" variable at the end and got a valid response from SharePoint Online.