核心标识- ApplicationController错误

Question

我在关注一座纪念碑：https://www.c-sharpcorner.com/article/asp-net-core-mvc-authentication-and-role-based-authorization-with-asp-net-core/

我在AplpicationController中有一个错误，我不确定如何修复它。我真的很感谢你的帮助

在下面的Index()方法中，我收到了下面这一行的错误: NumberOfUsers = r.Users.Count -- ApplicationRole没有包含用户的定义...

下面是ApplicationController类：

public IActionResult Index()
        {
            List<ApplicationRoleListViewModel> model = new List<ApplicationRoleListViewModel>();
            model = roleManager.Roles.Select(r => new ApplicationRoleListViewModel
            {
                RoleName = r.Name,
                Id = r.Id,
                Description = r.Description,
                NumberOfUsers = r.Users.Count
            }).ToList();
            return View(model);

这是ApplicationRoleListViewModel

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace CoreRole.Models
{
    public class ApplicationRoleListViewModel
    {
        public string Id { get; set; }
        public string RoleName { get; set; }
        public string Description { get; set; }
        public int NumberOfUsers { get; set; }
    }
}

Answer 1

我建议这样做: NumberOfUsers = (r.Users != null)？r.Users.Count :0

您只能对非null的列表执行计数。如果列表为空，则计数为零