c# - Entity framework and ASP.NET Identity -

using asp.net mvc 5 , entity framework 6, trying save new record package database. have following model entities:

user.cs (applicationuser in default template)

public class user : identityuser {     private icollection<package> packages;      public user()     {         this.packages = new hashset<package>();     }      public virtual icollection<package> packages     {         { return this.packages; }         set { this.packages = value; }     }      ... } 

package.cs

public class package {     private icollection<user> maintainers;      public package()     {         this.maintainers = new hashset<user>();     }      [required]     public virtual icollection<user> maintainers     {                 {             return this.maintainers;         }          set         {             this.maintainers = value;         }     }      ... } 

i have following dbcontext class:

public class applicationdbcontext : identitydbcontext<user>, iapplicationdbcontext {     public applicationdbcontext()         : base("defaultconnection", throwifv1schema: false)     {     }      public virtual idbset<package> packages { get; set; }      ...      public static applicationdbcontextcreate()     {         return new applicationdbcontext();     } } 

i have packageservice.cs (similar service pattern):

public class packagesservice : ipackagesservice {     private readonly irepository<package> packages;      public packagesservice(irepository<package> packages)     {         this.packages = packages;     }       public package create(ilist<user> maintainers)     {         var newpackage = new package         {             maintainers = maintainers         };          this.packages.add(newpackage);         this.packages.savechanges();          return newpackage;     } } 

i have standard implementation of irepository genericrepository: source code here.

now problem i'm having when create() method called entity framework throws following exception:

an exception of type 'system.invalidoperationexception' occurred in entityframework.dll not handled in user code

additional information: entity object cannot referenced multiple instances of ientitychangetracker.

i understand problem package entity change-tracked 2 different dbcontexts, use same applicationdbcontext through entire application. moreover, here's how inject (using ninject):

kernel.bind<dbcontext>().to<applicationdbcontext>().inrequestscope(); kernel.bind(typeof(irepository<>)).to(typeof(genericrepository<>)); kernel.bind<iuserstore<user>>().to<userstore<user>>().withconstructorargument("context", kernel.get<dbcontext>()); kernel.bind<usermanager<user>>().toself(); 

this part confuses me most. not bind context ninject, wherever use i.e usermanager, through owin instance, creates create() static method of same dbcontext. how there 2 dbcontext instances?

i've spent whole day debugging , can't understand why it's happening. in advance.

i'm not sure whether problem di bindings , ninject in particular, managed find workaround. since apparently had 2 instances of dbcontext, instead of using records first 1 mapped many-to-many relationship primary keys only. along following lines:

if (maintainerids != null && maintainerids.count > 0) {     foreach (string maintainerid in maintainerids)     {         var maintainer = new user() { id = maintainerid };         users.attach(maintainer);         newpackage.maintainers.add(maintainer);     } } 

this doesn't require dbcontext long ids match.