在Select表达式中使用Contains

Question

我想创建一个CheckboxList，其中用户的角色被选中，并显示所有可用选项，UI是ok的。但是下面的代码不能工作

        var applicationUser = db.AspNetUsers.Include(x => x.AspNetRoles)
                              .FirstOrDefault(x => x.Id == id.Value);
        if (applicationUser == null)
        {
            return HttpNotFound();
        }

        var model = new ViewModels.UsuarioViewModel();
        model.Id = applicationUser.Id;
        model.UserName = applicationUser.UserName;
        model.Name = applicationUser.Name;
        model.Email = applicationUser.Email;
        model.EmailConfirmed = applicationUser.EmailConfirmed;
        model.PhoneNumber = applicationUser.PhoneNumber;
        model.PhoneNumberConfirmed = applicationUser.PhoneNumberConfirmed;
        model.Active = applicationUser.Active;

        model.RolesList = db.AspNetRoles.Select(r => new SelectListItem
                            {
                                Selected =
                               applicationUser.AspNetRoles.Contains(x => x.Id == r.Id),
                                Text = r.Name,
                                Value = r.Name
                            }).ToList();
        return View(model);

角色列表是一个IEnumerable SelectListItem

问题是"selected = applicationUser.AspNetRoles"。包含(x => x. id == r.Id)"部分。

编辑:

好的，现在我有一个工作代码:

model.RolesList = db.AspNetRoles.ToList().Select(r => new SelectListItem
                            {
                                Selected = (applicationUser.AspNetRoles.
                                           Where(x => x.Id == r.Id).ToList().Count > 0),
                                //Selected = false,
                                Text = r.Name,
                                Value = r.Name
                            });

我无法使用Contains使它工作。

我想知道在这个表达式中是否有使用contains的方法。

Answer 1

你不想要contains，你想要any

Selected = applicationUser.AspNetRoles.Any(x => x.Id == r.Id),

contains查看给定元素是否在集合中，根本不是同一件事，我很惊讶您的代码甚至编译