c# - 在第一个 winform 页面中设置标签文本以显示在第二个表单页面上

Question

我是 C# 的新手，所以如果我的术语不符合标准，请原谅我。在我的 winform 应用程序中，我想从 MySQL 数据库@登录中获取一个名称，并在第二页 (home.cs) 上显示该名称。我目前收到一个错误，即“非静态字段需要对象引用。在 login.cs 中，我试图添加类似 -> Home.bunifuCustomLabel2.Text = "test"; 的内容来设置home.cs 中的标签基本上... Login.cs 是我的第一个加载页面，Home.cs 是我的第二个页面，它在成功登录后加载。我想在连接打开时查询数据库并最终设置标签文本让 home.cs 显示类似 Welcome, Name

的内容

登录.CS:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;

namespace Firemax
{
    public partial class Login : Form
    {
        MySqlConnection con = new MySqlConnection(@"Data Source=xyz.com;port=3333;Initial Catalog = test_db;User Id = fml;password=imscrewed");
        int i;
        public Login()
        {
            InitializeComponent();
            this.CenterToScreen();
        }

        private void BunifuMaterialTextbox1_OnValueChanged(object sender, EventArgs e)
        {

        }

        private void BunifuMaterialTextbox2_OnValueChanged(object sender, EventArgs e)
        {
            bunifuMaterialTextbox2.isPassword = true;
        }

        private void BunifuFlatButton1_Click(object sender, EventArgs e)
        {
            i = 0;
            con.Open();
            MySqlCommand cmd = con.CreateCommand();
            cmd.CommandType = CommandType.Text;
            cmd.CommandText = "select * from users where username='" + bunifuMaterialTextbox1.Text + "' and password='" + bunifuMaterialTextbox2.Text + "'";
            cmd.ExecuteNonQuery();
            DataTable dt = new DataTable();
            MySqlDataAdapter da = new MySqlDataAdapter(cmd);
            da.Fill(dt);
            i = Convert.ToInt32(dt.Rows.Count.ToString());

            if (i==0)
            {
                bunifuCustomLabel3.Text = "You have entered either a wrong Username and/or Password";

                Home.bunifuCustomLabel2.Text = "test";
            }
            else
            {
                this.Hide();
                Home fm = new Home();
                fm.Show();
                fm.Location = this.Location;
            }
            con.Close();

        }

        private void BunifuMaterialTextbox1_OnValueChanged_1(object sender, EventArgs e)
        {

        }

        private void BunifuImageButton1_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}

主页.CS:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;

namespace Firemax
{
    public partial class Home : Form
    {
        public Home()
        {
            InitializeComponent();
            this.CenterToScreen();
        }

        private void BunifuImageButton1_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}

Answer 1

欢迎来到 C# 世界!将 logic.cs 的代码更改为以下将消除您面临的问题。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;

namespace Firemax
{
    public partial class Login : Form
    {
        MySqlConnection con = new MySqlConnection(@"Data Source=xyz.com;port=3333;Initial Catalog = test_db;User Id = fml;password=imscrewed");
        int i;
        public Login()
        {
            InitializeComponent();
            this.CenterToScreen();
        }

        private void BunifuMaterialTextbox1_OnValueChanged(object sender, EventArgs e)
        {

        }

        private void BunifuMaterialTextbox2_OnValueChanged(object sender, EventArgs e)
        {
            bunifuMaterialTextbox2.isPassword = true;
        }

        private void BunifuFlatButton1_Click(object sender, EventArgs e)
        {
            i = 0;
            con.Open();
            MySqlCommand cmd = con.CreateCommand();
            cmd.CommandType = CommandType.Text;
            cmd.CommandText = "select * from users where username='" + bunifuMaterialTextbox1.Text + "' and password='" + bunifuMaterialTextbox2.Text + "'";
            cmd.ExecuteNonQuery();
            DataTable dt = new DataTable();
            MySqlDataAdapter da = new MySqlDataAdapter(cmd);
            da.Fill(dt);
            i = Convert.ToInt32(dt.Rows.Count.ToString());

            Home fm = new Home();
            if (i==0)
            {
                bunifuCustomLabel3.Text = "You have entered either a wrong Username and/or Password";

                fm.bunifuCustomLabel2.Text = "test";
            }
            else
            {
                this.Hide();                
                fm.Show();
                fm.Location = this.Location;
            }
            con.Close();

        }

        private void BunifuMaterialTextbox1_OnValueChanged_1(object sender, EventArgs e)
        {

        }

        private void BunifuImageButton1_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}

您的代码需要改进。我强烈建议在 C# video series 上投入 70 分钟莫什。