ASP.NET Core Identity 中的用户角色

RolesInUserViewModel：

namespace StudentManagement.ViewModels
{
    public class RolesInUserViewModel
    {
        public string RoleId { get; set; }
        public string RoleName { get; set; }
        public bool IsSelected { get; set; }
    }
}

用户角色管理方法：

[HttpGet]
public async Task<IActionResult> ManageUserRoles(string userId)
{
    ViewBag.userId = userId;
    var user = await _userManager.FindByIdAsync(userId);
    if (user == null)
    {
        ViewBag.ErrorMessage = $"无法找到 Id {userId} 的用户";
        return View("NotFound");
    }
    var model = new List<RolesInUserViewModel>();
    foreach (var role in _roleManager.Roles)
    {
        var rolesInUserViewModel = new RolesInUserViewModel
        {
            RoleId = role.Id,
            RoleName = role.Name,
            IsSelected = await _userManager.IsInRoleAsync(user, role.Name)
        };
        model.Add(rolesInUserViewModel);
    }
    return View(model);
}
[HttpPost]
public async Task<IActionResult> ManageUserRoles(List<RolesInUserViewModel> model, string userId)
{
    var user = await _userManager.FindByIdAsync(userId);
    if (user == null)
    {
        ViewBag.ErrorMessage = $"无法找到 Id {userId} 的用户";
        return View("NotFound");
    }
    var roles = await _userManager.GetRolesAsync(user);
    // 移除当前用户中的所有角色信息
    var removeRolesResult = await _userManager.RemoveFromRolesAsync(user, roles);
    if (!removeRolesResult.Succeeded)
    {
        ModelState.AddModelError("", "无法删除用户中的现有角色");
        return View(model);
    }
    // 查询出模型列表中选中的 RoleName 添加到用户中
    var addRolesResult = await _userManager.AddToRolesAsync(user, model.Where(x => x.IsSelected).Select(y => y.RoleName));
    if (!addRolesResult.Succeeded)
    {
        ModelState.AddModelError("", "无法向用户中添加选定的角色");
        return View(model);
    }
    return RedirectToAction("EditUser", new { Id = userId });
}

用户角色管理视图：

@model List<RolesInUserViewModel>
@{
    var userId = ViewBag.userId;
}
<form method="post">
    <div class="card">
        <div class="card-header">
            <h2>管理用户中的角色</h2>
        </div>
        <div class="card-body">
            @for (var i = 0; i < Model.Count; i++)
            {
                <div class="form-check m-1">
                    <input type="hidden" asp-for="@Model[i].RoleId" />
                    <input type="hidden" asp-for="@Model[i].RoleName" />
                    <input asp-for="@Model[i].IsSelected" class="form-check-input" />
                    <label class="form-check-label" asp-for="@Model[i].IsSelected">
                        @Model[i].RoleName
                    </label>
                </div>
            }
            <div asp-validation-summary="All" class="text-danger"></div>
        </div>
        <div class="card-footer">
            <input type="submit" value="更新" class="btn btn-primary" style="width: auto" />
            <a class="btn btn-primary" style="width: auto" asp-action="EditUser" asp-route-id="@userId">取消</a>
        </div>
    </div>
</form>

效果：