Question

我现在正在通过在课堂上构建登录系统来建立我的网站，

我几乎已经掌握了所有的东西，但它不会返回值。

login.cs

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using IndholdName;

namespace LoginClass
{
    public class Login
    {
        public LoginInfo LoginIndhold(string username, string password)
        {
            SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ToString());
            SqlCommand cmd = new SqlCommand();

            cmd.Connection = conn;

            cmd.CommandText = "SELECT Id FROM users WHERE Username = @Username AND Password = @Password";
            cmd.Parameters.AddWithValue("@Username", username);
            cmd.Parameters.AddWithValue("@Password", password);

            conn.Open();
            SqlDataReader readerbruger = cmd.ExecuteReader();

            if (readerbruger.Read())
            {
                HttpContext.Current.Session["id"] = Int32.Parse(readerbruger["id"].ToString());
                //It will not return a value
                //its error are here,
                return username + password;
            }
        }
    }
}

但这也是我设置它给集合赋值的方式;得到;

name.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace IndholdName
{
    public class LoginInfo
    {
        public string username { set; get; }
        public string password { set; get; }
    }
}

我的问题在于，它不会给用户带来价值，只有欢迎卡斯珀奥尔森的用户

if (readerbruger.Read())
        {
            HttpContext.Current.Session["id"] = Int32.Parse(readerbruger["id"].ToString());
            //It will not return a value
            //its error are here,
            return username + password;
        }

Answer 1

您的LoginIndhold方法有两个问题：

您已经说明它应该返回LoginInfo，而您又会返回连接的字符串。
如果readerbruger.Read()返回false，则您的方法根本不会返回值。

你想要做这样的事情：

if (readerbruger.Read())
{
      HttpContext.Current.Session["id"] = Int32.Parse(readerbruger["id"].ToString());
 }

 return new LoginInfo { Username = username, Password = password };

Answer 2

此方法：

public LoginInfo LoginIndhold(string username, string password)

表示返回值是LoginInfo类。你正在返回一个字符串。所以你需要在其中创建类存储登录信息并返回它。

尝试：

public LoginInfo LoginIndhold(string username, string password)
{
    IndholdName.LoginInfo info;
    SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ToString());
    SqlCommand cmd = new SqlCommand();

    cmd.Connection = conn;

    cmd.CommandText = "SELECT Id FROM users WHERE Username = @Username AND Password = @Password";
    cmd.Parameters.AddWithValue("@Username", username);
    cmd.Parameters.AddWithValue("@Password", password);

    conn.Open();
    SqlDataReader readerbruger = cmd.ExecuteReader();

    if (readerbruger.Read())
    {
        HttpContext.Current.Session["id"] = Int32.Parse(readerbruger["id"].ToString());
        info.username = username;
        info.password = password;
    }

    return info;
}

Answer 3

public LoginInfo LoginIndhold(string username, string password)
{
 LoginInfo returnValue =  null;
        using( SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ToString()))
   {
        SqlCommand cmd = new SqlCommand();

        cmd.Connection = conn;

        cmd.CommandText = "SELECT Id FROM users WHERE Username = @Username  AND Password = @Password";
        cmd.Parameters.AddWithValue("@Username", username);
        cmd.Parameters.AddWithValue("@Password", password);

        conn.Open();
       using(SqlDataReader readerbruger = cmd.ExecuteReader())
       {
        if (readerbruger.Read())
        {
            HttpContext.Current.Session["id"] =     Int32.Parse(readerbruger["id"].ToString());
            returnValue = new LoginInfo { Username= username, Password=  password};
        }
       }
    }

return returnValue;
}

它不会在课堂上返回一个值

3 个答案: