EntityState.Modified Error "entity of the same type already has the same primary key value"

Question

I got following error while running Edit [Post] method:

Attaching an entity of type 'MyType.Models.ApplicationUser' failed because another entity of the same type already has the same primary key value. This can happen when using the 'Attach' method or setting the state of an entity to 'Unchanged' or 'Modified' if any entities in the graph have conflicting key values. This may be because some entities are new and have not yet received database-generated key values. In this case use the 'Add' method or the 'Added' entity state to track the graph and then set the state of non-new entities to 'Unchanged' or 'Modified' as appropriate.

I create a new instance of ApplicationUser class (Identity framework) with all required fields and save it to database for an existing user, as a response to user "Edit" [Post] action, 'db' is a private variabile of type MyDbContext. I simplified code for readability.

Here is my controller:

public ActionResult Edit([Bind(Include = "Id,a,b,c,d,e")] ModelClass editParam)
    {
            ApplicationUser user = new ApplicationUser()
            {
                Id = editParam.Id,
                a= editParam.a,
                b = editParam.b,
                c= editParam.c,
                d= editParam.d,
                e= editParam.e,
            };

            string[] userRoles = editParam.Roles.Split(new[] { ", " }, StringSplitOptions.None); 
            var userStore = new UserStore<ApplicationUser>(db);
            var userManager = new UserManager<ApplicationUser>(userStore);


            userManager.RemoveFromRoles(user.Id, GetAllUserRoles()); 
            userManager.AddToRoles(user.Id, userRoles);
            db.Entry(user).State = EntityState.Modified;
            db.SaveChanges();
            return RedirectToAction("UsersList");
    }

This is my model class:

public class ModelClass
    {
            public string Id { get; set; }

            [Required]
            public string a { get; set;}

            [Required]          
            public string b { get; set; }

            [Required]
            public string c { get; set; }

            [Required]
            public string d { get; set; }

            [Required]
            public string e { get; set; }

            [Required]
            public string f { get; set; }

            [Required]
            public string g { get; set; }

            [Required]
            public string h { get; set; }   

            public int i { get; set; }
    }

You need to put an AsNoTracking() in linq for your user entity, the first time it is called. — kblau
@Simon , It would mean to change a big part of the code and I had problems listing user Roles using ApplicationUser class provided by Identity framework instead of using a custom Model Class which I do now. — user7739387
var DbQuery = db.Users.AsNoTracking().SingleOrDefault(user => user.Id == Id);" But if you are not getting users from the db twice, then there is another issue. — kblau
@kblau , Thanks for answering regarding use of '.AsNoTracking()' method. I have a class where same db context variable is used multiple times, do I need to set '.AsNoTracking()' everywhere or I can use something to prevent getting same user twice which I think is the case here ? I set it in the last query to db before Edit [Post] method and error is still present/the same. Thanks. — user7739387

kblau kblau · Accepted Answer · 2017-06-14T19:34:46

Can you please tell me what happens, when you try this?:

//I named my dbcontext, yours has a different class name
//My class name, as an example, is called NoId, yours is different
using (BreazEntities29 entity = new BreazEntities29())
{
    var id = entity.NoIds.Where(r => r.Id == 1).ToList();

    //if you are calling into a method, where you can not have control of AsNoTracking(),
    //then you can put the foreach statement shown here after calls into db change methods

    //credit to https://stackguides.com/questions/27423059/how-do-i-clear-tracked-entities-in-entity-framework
    //foreach (var db in entity.ChangeTracker.Entries())
    //{
    //    db.State = EntityState.Detached;
    //}

    NoId noid = new NoId { Id = 1, NoId1 = "new" };
    entity.Entry(noid).State = EntityState.Modified;
}

return RedirectToAction("UsersList");

EntityState.Modified Error "entity of the same type already has the same primary key value"

1 Answers