C# add a header, specifically Authorization header to SharePoint's ClientContext

A-Gon350 

If you want to add additional headers to CSOM Clientcontext then you can modify the executing webrequest like described here "https://sharepointdragons.com/2012/04/20/authentication-when-using-the-sharepoint-client-object-model/"

ClientContext clientContext = new ClientContext("http://thesitecollection");
clientContext.ExecutingWebRequest += new EventHandler<WebRequestEventArgs(clientContext_ExecutingWebRequest);

Web site = clientContext.Web;
clientContext.Load(site);
clientContext.ExecuteQuery();

 

static void clientContext_ExecutingWebRequest(object sender, WebRequestEventArgs e){
    e.WebRequestExecutor.WebRequest.Headers.Add("X-FORMS_BASED_AUTH_ACCEPTED", "f");
}

 

But you might not need to go through all that hassle if you use Authenticationmanager from the PnP.Framework Library

https://github.com/pnp/pnpframework/blob/dev/src/lib/PnP.Framework/AuthenticationManager.cs

It gives you many authentication methods that just return a ClientContext object.

AuthenticationManager auth = AuthenticationManager.CreateWithCredentials(username,password);

ClientContext ctx = auth.GetContext(siteUrl);