c# - 从 foreach 循环 ASP.NET Core 5.0 返回一个变量

Question

我正在尝试从 foreach 循环返回密码以进行一些验证，但我无法返回密码变量。我不断收到错误。我在我的控制器中执行此操作。

我的代码：

[HttpPost]
public IActionResult Login(userModel user)
{
    ViewBag.Password = pwd.GetPassword(user);

    string password = "";
    foreach(var pwdR in ViewBag.Password.Rows)
    {
       password = pwdR[1];
    }
    return password; // Here I get this error: CS0029: Cannot implicitly convert type 'string' to 'Microsoft.AspNetCore.Mvc.IActionResult'

    // VALIDATION CODE
    ....................
}

我究竟做错了什么？

谢谢！

更新：

[HttpPost]
public IActionResult Login(userModel user)
{
    ScryptEncoder enc = new ScryptEncoder();
    UserModel pwd = new UserModel();
    ViewBag.Password = pwd.GetPassword(user);

    string password = "";
    foreach(var pwdR in ViewBag.Password.Rows)
    {
       password = pwdR[1];
    }
    return password; // Here I get this error: CS0029: Cannot implicitly convert type 'string' to 'Microsoft.AspNetCore.Mvc.IActionResult'

    // VALIDATION CODE
    bool match = enc.Compare(user.pwd, password);

    if (match) 
    {
        ViewBag.Error = "You are now logged in.";
        return View();
    } else
    {
        ViewBag.Error = "Login failed.";
        return View();
    }
}

标签： c#asp.netasp.net-core.net-core

Answer 1

加载所有用户并找到您需要的用户是一个很大的性能错误。

试试这个代码

[HttpPost]
public IActionResult Login(UserModel user)
{
    ScryptEncoder enc = new ScryptEncoder();

      var userNamePassword= GetUserNamePassword (user) ;

  if(  userNamePassword==null)
    ViewBag.Error = "Login failed. User is not found";
    return View();
}
    // VALIDATION CODE
    bool match = enc.Compare(userNamePassword.Password, password);

    if (match) 
    {
        ViewBag.Error = "You are now logged in.";
        return View();
    } else
    {
        ViewBag.Error = "Login failed.";
        return View();
    }
}

将您的模型类更改为此

 public class UserNamePasswordModel
    {
        public string Username { get; set; }

        public string Password { get; set; }

    } 

并将此代码放在登录操作附近的某个位置

private  UserNamePasswordModel GetUserNamePassword (UserModel user)
{

UserNamePasswordModel  userNamePassword= null;

var connectionString = "Server=localhost;Database=xxxx; uid = xxxx;Password=xxxx;";
        
using   (var connection = new MySqlConnection(connectionString))
{
  var command =  new MySqlCommand("SELECT UserName, Password  FROM User WHERE Username = @Username", connection);

command.Parameters.AddWithValue("@Username", user.Username);

        connection.Open();

       var reader = command.ExecuteReader();

        if (reader.HasRows)
        {
           if reader.Read()
            {
             userNamePassword= new UserNamePasswordModel
             {
              Username=  reader.GetString(0),
               Password =   reader.GetString(1)
             };
            }
        }
        
        reader.Close();
    }
}
    return userNamePassword;
       
}