如何在用户控件中为标签添加值？ [英] How add value to a label in user control?

问题描述

嗨！



我有一个注册表，一个登录表和一个主表。该程序从注册表开始。如果我注册数据（名称，电子邮件，密码）加载到本地数据库。当我正确登录显示主窗体。主窗体具有带标签的usercontrol。我想用她/他的名字在标签上写一个欢迎文本。示例：欢迎Josh！。所以我应该识别用户，所以我使用登录表单中的textboxEmail.Text。它没有显示价值。



我尝试过：

Hi!

I have a registration form, a login form and a Main form.The program start with registration form. If i sign up the datas(name, email, password) load up to the local database. When i log in correctly show the main form. The main form has a usercontrol with a label. I would like to write a welcome text to the label with her/his name. Example: "Welcome Josh!". So I should to identify the user, so i use the textboxEmail.Text from the login form. It don't show the value.

What I have tried:

namespace personalFinance
{
   public partial class Login : Form
      {
        public Login()
         {

            InitializeComponent();
            var MainForm = new MainForm();
            MainForm.Show();
            HomepageUC hp = new 
            HomepageUC(textboxEmail.Text);
            hp.Show();
         } 
      }

}





public partial class HomepageUC : UserControl
{
   string login = "";

   public HomepageUC()
   {
       InitializeComponent();
   }

   public HomepageUC(string email): this() 
      {
       login = email;
        var conn = new SqlConnection(@"Server=(localdb)\MSSQLLocalDB; 
        AttachDbFileName=|DataDirectory|database.mdf;");
        conn.Open();
         try
            {
              conn.Open();
              var cmd = new SqlCommand($"SELECT name FROM registration_data WHERE email = '{login}'", conn);
               var reader = cmd.ExecuteReader();
               while (reader.Read()) labelWelcome.Text = reader[0].ToString();
            }
            
            finally
            {
                conn.Close(); 
            }
      }
 }

推荐答案

SELECT name FROM registration_data WHERE email ='{login }'，conn）;
var reader = cmd.ExecuteReader（）;
while（reader.Read（））labelWelcome.Text = reader [0] .ToString（）;
}

最后
{
conn.Close（）;
}
}
}

"SELECT name FROM registration_data WHERE email = '{login}'", conn); var reader = cmd.ExecuteReader(); while (reader.Read()) labelWelcome.Text = reader[0].ToString(); } finally { conn.Close(); } } }

不要 - 将用户控件的内部工作暴露给外界。

相反，请看这里：传输信息两种表格之间，第1部分：父母与子女 [ ^ ] - 它专注于表单，但控件的原则（甚至代码）完全相同（因为Form派生自Control）

Don't - that exposes the internal workings of the user control to the outside world.
Instead, see here: Transferring information between two forms, Part 1: Parent to Child[^] - it focusses on forms, but the principles (and even the code) are exactly the same for controls (because Form is derived from Control)

这篇关于如何在用户控件中为标签添加值？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！