ASP.NET 5 MVC 6和Entity Framework 7问题

Question

We can't add Owin and Entity framework 7 together. As we do so then there will be ambiguity between Microsoft.AspNet.Identity.core 2.0.0.0 and Microsoft.AspNet.Identity 3.0.0 Beta1

And hence I am not able to implement role provider in my application to manage the user roles.

After facing this issue I removed Owin references and created UserManager using Microsoft.AspNet.Identity 3.0.0 and EF 7 but UserManager.AddToRoleAsync(user, roleName) always throws exception as below:-

InvalidOperationException: The instance of entity type 'Mozaics.DAL.Models.ApplicationUser' cannot be tracked because another instance of this type with the same key is already being tracked. For new entities consider using an IIdentityGenerator to generate unique key values.

Code snippet is like this.

 public async Task<ActionResult> RoleAddToUser(string UserName, string RoleName)
    {
        var user = context.Users.Where(u => u.UserName.Equals(UserName, StringComparison.CurrentCultureIgnoreCase)).FirstOrDefault();

        var result = await UserManager.AddToRoleAsync(user,  RoleName );

        ViewBag.ResultMessage = "Role created successfully !";
        var list = context.Roles.OrderBy(r => r.Name).ToList().Select(rr => new SelectListItem { Value = rr.Name.ToString(), Text = rr.Name }).ToList();
        ViewBag.Roles = list;

        return View("ManageUserRoles");
    }

Answer 1

@sanjaypujari

Just try that one:

var user = await context.FindByNameAsync(UserName);
ApplicationUser appuser = (ApplicationUser)user;
var result = await UserManager.AddToRoleAsync(appuser,  RoleName);

When executed like this, ApplicationUser shouldn't be tracked twice. Same thing helps, too, if you want to update a ApplicationUser.

Answer 2

I run to this issue. One solution that worked for me was that getting the user via the UserManager and then adding the role:

instead of

var user = context.Users.Where(u => u.UserName.Equals(UserName, StringComparison.CurrentCultureIgnoreCase)).FirstOrDefault();
var result = await UserManager.AddToRoleAsync(user,  RoleName );

use the following

var user = await UserManager.FindByNameAsync(UserName);
var result = await UserManager.AddToRoleAsync(user,  RoleName );