c# - ASP MVC Application User Null using User.Identity.GetUserId -

ok have relationship between applicationuser , questionresults, models below, userid nor username retrieved, need userid setup foreignkey on questionresults entity.

any appreciated error receiving below:

an exception of type 'system.nullreferenceexception' occurred in stra.dll not handled in user code  additional information: object reference not set instance of object. on these lines of code:  qr.user.id = user.identity.getuserid(); qr.user.username = user.identity.getusername(); 

models

public class questionresult     {         public questionresult()         {             datecreated = datetime.now;             datemodified = datetime.now;         }         public int id { get; set; }         public datetime? datecreated { get; set; }         public datetime? datemodified { get; set; }         public int questionscore { get; set; }         //navigation properties         public virtual applicationuser user { get; set; }         //public icollection<categoryresult> categoryresult { get; set; }         //public virtual category category { get; set; }         [notmapped]         public int categoryid { get; set; }         public virtual question question { get; set; }         public int questionid { get; set; }         //public virtual category category { get; set; }         //public int categoryid { get; set; }     } public class applicationuser : identityuser     {         public string firstname { get; set; }         public string surname { get; set; }         public string industry { get; set; }         public string globalregion { get; set; }         public string currentsituation { get; set; }         public int salesforcesize { get; set; }         public bool isverified { get; set; }         //navigation properties         public virtual icollection<categoryresult> categoryresult { get; set; }         public virtual icollection<questionresult> questionresult { get; set; }         //public virtual icollection<report> report { get; set; }         //public virtual icollection<surveyresult> surveyresult { get; set; }         public virtual organisation organisation { get; set; }         public int? organisationid { get; set; }          public async task<claimsidentity> generateuseridentityasync(usermanager<applicationuser> manager)         {             // note authenticationtype must match 1 defined in cookieauthenticationoptions.authenticationtype             var useridentity = await manager.createidentityasync(this, defaultauthenticationtypes.applicationcookie);             // add custom user claims here             return useridentity;         }      } 

your code equivalent this::

var user = qr.user; user.id = user.identity.getuserid(); 

if questionresult linked user not changing user linked questionresult, changing id of existing user - , not allowed anyway.

but questionresult not linked user. qr.user null - null reference exception.

in general, life easier in entity framework if add foreign key model:

public class questionresult {    public string userid { get; set; }     public virtual applicationuser user { get; set; } } 

and can set foreign key directly:

qr.userid = user.identity.getuserid();

references:

why entity framework reinsert existing objects database?

making absent foreign keys