从角色中删除用户

Question

我正在制作一个简单的小型web应用程序项目来更好地学习，并使用带有身份的asp.net核心6.0mvc，我有两个角色，管理和用户。我想给管理员一个阻止用户的可能性。为此，我知道我必须创造第三个角色，但由于我仍然是个初学者，我不知道下一步该做什么。我发现了许多类似于这个https://csharp-video-tutorials.blogspot.com/2019/07/add-or-remove-users-from-role-in-aspnet.html的教程，但它们都有一些我无法访问的共同之处，userManager。示例

[HttpGet]
public async Task<IActionResult> EditUsersInRole(string roleId)
{
    ViewBag.roleId = roleId;

    var role = await roleManager.FindByIdAsync(roleId);

    if (role == null)
    {
        ViewBag.ErrorMessage = $"Role with Id = {roleId} cannot be found";
        return View("NotFound");
    }

    var model = new List<UserRoleViewModel>();

    foreach (var user in userManager.Users)
    {
        var userRoleViewModel = new UserRoleViewModel
        {
            UserId = user.Id,
            UserName = user.UserName
        };

        if (await userManager.IsInRoleAsync(user, role.Name))
        {
            userRoleViewModel.IsSelected = true;
        }
        else
        {
            userRoleViewModel.IsSelected = false;
        }

        model.Add(userRoleViewModel);
    }

    return View(model);
}

userManager.Users给出一个错误“名称'userManager‘在当前上下文中不存在”，roleManager.FindByIdAsync也给出了相同的错误

我使用的是ApplicationUser类

public class ApplicationUser : IdentityUser
    {
        public virtual Profile? Profile { get; set; }
    }

ApplicationDbContext是

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
            : base(options)
        {
        }

        public ApplicationDbContext() {}

        public DbSet<Profile> Profiles { get; set; }


        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            string connection = @"Server=(localdb)\mssqllocaldb;Database=ExerciseDb; Trusted_Connection=True;";
            optionsBuilder.UseLazyLoadingProxies().UseSqlServer(connection);
        }

        protected override void OnModelCreating(ModelBuilder builder)
        {
            base.OnModelCreating(builder);
            builder.HasDefaultSchema("Identity");
            builder.Entity<IdentityUser>(entity =>
            {
                entity.ToTable(name: "User");
            });
            builder.Entity<IdentityRole>(entity =>
            {
                entity.ToTable(name: "Role");
            });
            builder.Entity<IdentityUserRole<string>>(entity =>
            {
                entity.ToTable("UserRoles");
            });
            builder.Entity<IdentityUserClaim<string>>(entity =>
            {
                entity.ToTable("UserClaims");
            });
            builder.Entity<IdentityUserLogin<string>>(entity =>
            {
                entity.ToTable("UserLogins");
            });
            builder.Entity<IdentityRoleClaim<string>>(entity =>
            {
                entity.ToTable("RoleClaims");
            });
            builder.Entity<IdentityUserToken<string>>(entity =>
            {
                entity.ToTable("UserTokens");
            });

            builder.Entity<ApplicationUser>()
                .HasOne(a => a.Profile)
                .WithOne(p => p.ApplicationUser)
                .HasForeignKey<Profile>(p => p.ApplicationUserId);

            builder.Entity<IdentityRole>().HasData(
                new IdentityRole() { Id = "1", Name = "Admin" },
                new IdentityRole() { Id = "2", Name = "Client" }
                new IdentityRole() { Id = "3", Name = "Authorized" }
            );

Answer 1

您还没有定义变量userManager和roleManager。你指的是尚未被定义的事物。

请参见前面关于如何定义和初始化UserManager：How do i create an instance of UserManager实例的堆栈溢出问题。