使用 UserManager.IsInRoleAsync() 时出现 InvalidOperationException

Question

我正在尝试让所有用户担任我正在编辑的角色。但是当我加载页面时，它一直给我

InvalidOperationException: Cannot set MySqlCommand.CommandText when there is an open DataReader for this command; it must be closed first.

public async Task<IActionResult> EditRole(string id)
{
    var role = await roleManager.FindByIdAsync(id);
    if(role == null)
     {
        ViewBag.ErrorMessage = $"Role with id = {id} cannot be found";
        return View("NotFound");
    }
    var model = new EditRoleModel
    {
        Id = role.Id,
        RoleName = role.Name
    };
    foreach(var user in userManager.Users)
    {
        var userInRole = await userManager.IsInRoleAsync(user, role.Name);
        if (userInRole)
        {
            model.Users.Add(user.UserName);
        }
    }
    return View(model);
}

我在这里遇到错误

var userInRole = await userManager.IsInRoleAsync(user, role.Name);

Answer 1

Users 属性是一个 IQueryable<User>，它 看起来 就像在您对数据进行开放式流式查询时迭代它，如果您尝试执行第二个操作，这会导致问题。

因此，假设用户目录不是很大，您可以简单地解决这个问题：

foreach(var user in userManager.Users.ToList())
{...}

它在迭代之前急切地完成了第一个查询。

但是！您可能想看看 GetUsersInRoleAsync 而不是 :

foreach (var user in userManager.GetUsersInRoleAsync(role.Name))
{
    model.Users.Add(user.UserName);
}

使用 UserManager.IsInRoleAsync() 时出现 InvalidOperationException

Im getting InvalidOperationException when using UserManager.IsInRoleAsync()

c#

asp.net-core

asp.net-core-identity