Getting client context in provider hosted apps

Question

I am new to developing provider hosted apps and going through some code snippets over the web to see how to get the context of the host web (or app web) to work on lists and libraries etc through the app. I read through the OAUTH concepts and the token flow for context token and accesstoken.

I saw in some of the code snippets that the client context is obtained using

var spContext = SharePointContextProvider.Current.GetSharePointContext(HttpContext);    
using (var clientContext = spContext.CreateUserClientContextForSPHost())

However at a few places it is retrieved using the contexttoken

var contextToken = TokenHelper.GetContextTokenFromRequest(Page.Request);
var hostWeb = Page.Request["SPHostUrl"];
using (var clientContext = TokenHelper.GetClientContextWithContextToken(hostWeb, contextToken, Request.Url.Authority))

So my question is, when are we required to work with context and access tokens in the code to get the client context. Or is it that both the methods mentioned above essentially do the same thing and any one can be used to get the clientcontext ?

Answer 1

Contexttoken,

You can get the context of host web and app web to use SharePoint lists and libraries from your tenant and app as well. Contexttoken is mostly used in low-trust provider hosted app. In low-trust provider hosted app, you have to use Azure to host your web application. Azure is providing SPAppToken in url, by getting that you can get authentication token for app. SPHostUrl and SPAppWebUrl are also provided in url. You can get that from url and use that urls to get context.

Here you can get some reference about basic SharePoint Provider hosted app.

Some Links for reference

• http://blogs.msdn.com/b/kaevans/archive/2013/09/24/introducing-sharepointcontext-for-provider-hosted-sharepoint-apps.aspx
• http://www.sharepointpals.com/post/Getting-the-Client-Context-from-Claims-Aware-Provider-Hosted-Application-in-SharePoint-2013