Provider hosted app lauched from outside of Sharepoint

Question

In the past months i was developing provider hosted apps for Sharepoint 2013 online. Everything worked fine until i run into the following problem: in some cases for my customer it's not acceptable to start the provider hosted app from inside of Sharepoint (Site Contents / Clicking on the app's tile).

One of my tasks would be:

My customer has a corporate website (not hosted on Sharepoint). Once a form on this website is submitted by a visitor I should write an item into a Sharepoint list in the app web or the host web. Of course in this case nobody is logged in into Sharepoint, so the web part of the provider hosted app should be able to write data to a Sharepoint list without lauching it from inside Sharepoint, without a logged in user.

What do you think, is it possible? Maybe i could use app-only auth?

Thank you very much!

Answer 1

Yes, you can use app-only policy to access SharePoint Online. First step is to allow it in your app.manifest.

Second step may be little tricky. I did it about a year ago and it required to modify TokenHelper.cs file.

My case was simple, as I was making exclusively app-only calls. I did not use SharePointContext or SharePointContextFilterAttribute, so I removed them from my code. I relied on TokenHelper to create ClientContext.

I see now, that with current version of TokenHelper.cs no modifications are required. I've created new SharePoint App project in Visual Studio, removed files mentioned earlier and edited HomeController. user.Title returns "SharePoint App".

public ActionResult Index()
{
  var uri = new Uri("https://sample.sharepoint.com/sites/sample/");
  var accessToken = TokenHelper.GetAppOnlyAccessToken(TokenHelper.SharePointPrincipal, uri.Authority, TokenHelper.GetRealmFromTargetUrl(uri));
  using (var context = TokenHelper.GetClientContextWithAccessToken(uri.ToString(), accessToken.AccessToken))
  {
    var web = context.Web;
    var user = web.CurrentUser;

    context.Load(user, u => u.Title);
    context.ExecuteQuery();

    ViewBag.UserName = user.Title;
  }

  return View();
  }
}