Implement Microsoft Graph API in a .netcore API project - .net-core

Question

I am trying to write a .netcore API which gets a bearer token from third party Webapp. This .netcore API should access the Microsoft graph API and get the user group information back from Azure AD.
I was following the sample project https://github.com/Azure-Samples/active-directory-dotnet-webapp-webapi-openidconnect-aspnetcore.
But unfortunately this uses AAD graph rather tha Microsoft graph API.
I tried to implement Graph API in the .netcore api project in the above sample.
Things I have tried
I have changed the AAD graph to Graph API in the AzureAdAuthenticationBuilderExtensions.cs(in the web app project)
options.Resource = "https://graph.microsoft.com";
Also I used the Microsoft.Graph nuget in the API project. And I am trying to create the GraphServiceClient using the code below
public GraphServiceClient GetClient(string accessToken, IHttpProvider provider = null)
{
var words = accessToken.Split(' ');
var token = words[1];
var delegateAuthProvider = new DelegateAuthenticationProvider((requestMessage) =>
{
requestMessage.Headers.Authorization = new AuthenticationHeaderValue("bearer", token);
return Task.FromResult(0);
});
var graphClient = new GraphServiceClient(delegateAuthProvider, provider ?? new HttpProvider());
return graphClient;
}
And finally I am trying to access the user information using the code below,
public async Task<IEnumerable<Group>> GetGroupAsync(string accessToken)
{
var graphClient = GetClient(accessToken);
try
{
User me = await graphClient.Me.Request().GetAsync();
}
catch (Exception e)
{
Console.WriteLine(e);
throw;
}
var user= await graphClient.Users["***"].Request().Expand("MemberOf").GetAsync();
var userEmail = "testemail#test.com";
var usergroup = await graphClient.Users[userEmail].GetMemberGroups(false).Request().PostAsync();
var groupList = new List<Group>();
foreach (var g in usergroup.CurrentPage)
{
var groupObject = await graphClient.Groups[g].Request().GetAsync();
groupList.Add(groupObject);
}
return groupList;
}
But when I try the code I am getting the error "Microsoft.Graph.ServiceException: Code: InvalidAuthenticationToken
Message: Access token validation failure.Inner error at Microsoft.Graph.HttpProvider."
Can somebody help me please?
Thanks in advance

Answer 1

The access token passed to GetGroupAsync is not correct , and i am confused why you need to split the token :
var words = accessToken.Split(' ');
var token = words[1];
But never mind , since you have modified options.Resource = "https://graph.microsoft.com"; ADAL will help you get access token for Microsoft Graph API in OnAuthorizationCodeReceived function , and save the tokens to cache .
To get the access token , you could use ADAL to get the token from cache :
AuthenticationResult result = null;
// Because we signed-in already in the WebApp, the userObjectId is know
string userObjectID = (User.FindFirst("http://schemas.microsoft.com/identity/claims/objectidentifier"))?.Value;
// Using ADAL.Net, get a bearer token to access the TodoListService
AuthenticationContext authContext = new AuthenticationContext(AzureAdOptions.Settings.Authority, new NaiveSessionCache(userObjectID, HttpContext.Session));
ClientCredential credential = new ClientCredential(AzureAdOptions.Settings.ClientId, AzureAdOptions.Settings.ClientSecret);
result = await authContext.AcquireTokenSilentAsync("https://graph.microsoft.com", credential, new UserIdentifier(userObjectID, UserIdentifierType.UniqueId));
Then you could pass that token to your function:
await GetGroupAsync(result.AccessToken);
Modify your GetClient function to delete the split part:
public GraphServiceClient GetClient(string accessToken, IHttpProvider provider = null)
{
var delegateAuthProvider = new DelegateAuthenticationProvider((requestMessage) =>
{
requestMessage.Headers.Authorization = new AuthenticationHeaderValue("bearer", accessToken);
return Task.FromResult(0);
});
var graphClient = new GraphServiceClient(delegateAuthProvider, provider ?? new HttpProvider());
return graphClient;
}