asp.net - 为什么这违反了类型约束？

Question

我正在尝试自定义 ASP.NET Identity 3，以便它使用整数键:

public class ApplicationUserLogin : IdentityUserLogin<int> { }
public class ApplicationUserRole : IdentityUserRole<int> { }
public class ApplicationUserClaim : IdentityUserClaim<int> { }

public sealed class ApplicationRole : IdentityRole<int>
{
  public ApplicationRole() { }
  public ApplicationRole(string name) { Name = name; }
}

public class ApplicationUserStore : UserStore<ApplicationUser, ApplicationRole, ApplicationDbContext, int>
{
  public ApplicationUserStore(ApplicationDbContext context) : base(context) { }
}

public class ApplicationRoleStore : RoleStore<ApplicationRole, ApplicationDbContext, int>
{
  public ApplicationRoleStore(ApplicationDbContext context) : base(context) { }
}

public class ApplicationUser : IdentityUser<int>
{
}

public sealed class ApplicationDbContext : IdentityDbContext<ApplicationUser, ApplicationRole, int>
{
  private static bool _created;

  public ApplicationDbContext()
  {
    // Create the database and schema if it doesn't exist
    if (!_created) {
      Database.AsRelational().Create();
      Database.AsRelational().CreateTables();
      _created = true;
    }
  }
}

编译正常，但随后抛出运行时错误:

System.TypeLoadException

GenericArguments[0], 'TeacherPlanner.Models.ApplicationUser', on 'Microsoft.AspNet.Identity.EntityFramework.UserStore`4[TUser,TRole,TContext,TKey]' violates the constraint of type parameter 'TUser'.

UserStore 的签名是:

public class UserStore<TUser, TRole, TContext, TKey>
where TUser : Microsoft.AspNet.Identity.EntityFramework.IdentityUser<TKey>
where TRole : Microsoft.AspNet.Identity.EntityFramework.IdentityRole<TKey>
where TContext : Microsoft.Data.Entity.DbContext
where TKey : System.IEquatable<TKey>

ApplicationUser正是 IdentityUser<int> 。这不就是它要找的吗？

Answer 1

遇到这个问题。它在startup.cs 文件上崩溃。改变了

services.AddIdentity<ApplicationUser, ApplicationIdentityRole>()
                .AddEntityFrameworkStores<ApplicationDbContext>()
                .AddDefaultTokenProviders();

至

services.AddIdentity<ApplicationUser, ApplicationIdentityRole>()
                .AddEntityFrameworkStores<ApplicationDbContext,int>()
                .AddDefaultTokenProviders();

声明 key 类型似乎可以避免崩溃