我正试图弄清楚这应该是简单的......
我想获得所有用户的列表,在<.select>中选择一个,按一个按钮,获取该用户已分配的所有角色,这是失败的地方,这里是代码
public class RoleManagementModel : PageModel
{
private readonly RoleManager<ApplicationRole> _roleManager;
private readonly UserManager<ApplicationUser> _userManager;
public RoleManagementModel(RoleManager<ApplicationRole> roleManager,
UserManager<ApplicationUser> userManager)
{
_roleManager = roleManager;
_userManager = userManager;
}
[BindProperty]
public InputModel Input { get; set; }
public IList<ApplicationUser> UserList { get; set; }
public IList<string> UserRoleList { get; set; }
public IList<string> RoleList { get; set; }
public class InputModel
{
public string User { get; set; }
public string RoleToRemove { get; set; }
public string RoleToAdd { get; set; }
}
public async Task<IActionResult> OnGetAsync()
{
UserList = _userManager.Users.ToList();
UserRoleList = new List<string>();
RoleList = new List<string>();
return Page();
}
public async Task<IActionResult> OnPostGetRolesAsync()
{
var user = await _userManager.FindByNameAsync(Input.User);
UserRoleList = await _userManager.GetRolesAsync(user);
return Page();
}
}
这是Razor Page
<select asp-for="Input.User" class="..">
@foreach (ApplicationUser au in Model.UserList)
{
<option>@au.UserName</option>
}
</select>
<button class=".." type="submit" asp-page-handler="GetRoles">Get Roles </button>
<select asp-for="Input.RoleToRemove" class="..">
@foreach (string ur in Model.UserRoleList)
{
<option>@ur</option>
}
</select>
我尝试过以下方法:
在OnPostGetRolesAsync()之后返回Page()抛出异常
NullReferenceException:未将对象引用设置为对象的实例。
@foreach(Model.UserList中的ApplicationUser au)
我猜是因为OnGet没有运行而且UserList为空
如果我将其更改为RedirectToPage()然后OnGet被触发并将UserRoleList设置为一个新列表,我们回到正方形
删除UserRoleList = new List();在尝试打开页面时,OnGet将抛出相同的异常(但对于UserRoleList)
干杯
您在Get中加载UserList但您必须再次为post请求加载它
public async Task<IActionResult> OnGetAsync()
{
UserList = _userManager.Users.ToList();
UserRoleList = new List<string>();
RoleList = new List<string>();
return Page();
}
public async Task<IActionResult> OnPostGetRolesAsync()
{
UserList = _userManager.Users.ToList(); // You have to reload
var user = await _userManager.FindByNameAsync(Input.User);
UserRoleList = await _userManager.GetRolesAsync(user);
return Page();
}