Question

我有一个网络表单不符合我的预期，我有点难过。在表单上，电话号码从数据库填充到文本框。这部分工作正常。然后，用户可以选择编辑文本框中的值，然后按下一个按钮，该按钮使用文本框中的值更新数据库中的值。这是不起作用的部分。

这是我的代码。

using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Net;
using System.Net.Mail;
using System.Net.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

public partial class contact_edit : System.Web.UI.Page
{
    //sql connection here

    protected void Page_Load(object sender, EventArgs e)
    {
        string phoneNum = "";
        cn.Open();
        SqlCommand command = new SqlCommand("getContactInfo", cn);
        command.CommandType = CommandType.StoredProcedure;

        SqlDataReader myReader;
        myReader = command.ExecuteReader();

        while (myReader.Read())
        {
            phoneNum = myReader.GetString(3).ToString();
        }

        cn.Close();

        //If I take this part out and don't populate textbox,
        //my update works.  If I leave it, it does not
        phone.Text = phoneNum.ToString();

    }
    protected void update_btn_Click(object sender, EventArgs e)
    {
        cn.Open();

        phone.Text = "";

        string updatedPhone = phone.Text;

        string updateSQLString = "update contact set Phone_num = '" + updatedPhone +   
        "'";

        SqlCommand updateCommand = new SqlCommand(updateSQLString, cn);
        updateCommand.ExecuteNonQuery();

        cn.Close();
        Response.Redirect("contact_edit.aspx");
}

}

当我点击按钮调用我的更新方法时。它试图获得手机文本框的价值。但是在表单加载之后，我更改文本框值然后点击更新按钮，它会在表单加载时保持获取最初分配给文本框的值。为什么会这样？

Answer 1

尝试将if (!Page.IsPostBack)放在page_load代码

周围

protected void Page_Load(object sender, EventArgs e)
    {
       if (!Page.IsPostBack)
        {
        string phoneNum = "";
        cn.Open();
        SqlCommand command = new SqlCommand("getContactInfo", cn);
        command.CommandType = CommandType.StoredProcedure;

        SqlDataReader myReader;
        myReader = command.ExecuteReader();

        while (myReader.Read())
        {
            phoneNum = myReader.GetString(3).ToString();
        }

        cn.Close();

        //If I take this part out and don't populate textbox,
        //my update works.  If I leave it, it does not
        phone.Text = phoneNum.ToString();
     }

    }

Answer 2

为什么会这样？

因为您在每次回发时都从数据库加载值。将其包裹在IsPostBack中 - 检查：

protected void Page_Load(object sender, EventArgs e)
{
    if(!IsPostBack)
    {
        // only load the value on the first load
    }
}

Answer 3

protected void Page_Load(object sender, EventArgs e)
{

  if (!Page.IsPostBack)
  {
     //access data here
     //assign value here
     phone.Text = phoneNum.ToString();  
  }

}

文本框值未被抓取

3 个答案: