我有一个表单，其中有一个ListBox，一个文本框和四个名为Save，Edit，Delete和Clear的按钮。我从数据库中检索数据并填充ListBox。当我选择ListBox中的一个项目时，它将填充到文本框中。现在，当我删除该项目时，没有任何错误，它工作正常。但是当我尝试更新该项目时，即更改文本框中的文本然后单击Edit按钮时，就会出现问题。在文本框中，我可以看到文本正在被更改，没有问题，但是当我调试时，我发现在后端，文本框仍然包含旧文本而不是修改过的文本。
我做错了什么？
这是我的用户界面代码：
<asp:Content ID="Content3" ContentPlaceHolderID="MainContent" runat="server">
<h1>Employee Category</h1>
<table>
<td>
<asp:ListBox ID="listEmployeeCategory" runat="server" Height="164px" Width="210px" AutoPostBack="true" />
</td>
<td>
<table>
<tr>
<td>
<asp:Label ID="lblMessage" runat="server" Text="" Visible="false" />
</td>
</tr>
<tr>
<td>
<asp:Label ID="lblEmpCategoryName" runat="server" Text="Name: " Font-Bold="true" />
</td>
<td>
<asp:TextBox ID="txtEmpCategoryName" runat="server" />
</td>
<td>
<asp:RequiredFieldValidator ID="rqdEmpCategoryName" ControlToValidate="txtEmpCategoryName" ErrorMessage="Employee Category Name can't be empty!" Style="color:Red" runat="server" />
</td>
</tr>
</table>
<asp:Button ID="btnSave" Text="Save" runat="server" OnClick="btnSave_Click" />
<asp:Button ID="btnEdit" Text="Edit" runat="server" OnClick="btnEdit_Click" />
<asp:Button ID="btnDelete" Text="Delete" runat="server" OnClick="btnDelete_Click" />
<asp:Button ID="btnCancel" Text="Cancel" runat="server" />
</td>
</table>
</asp:Content>
这是我的后端代码，为了每个人的理解，我发布了我的整个后端代码（BL，DAL和DAO代码除外）：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using Shelter.DAO.MasterEntry;
using Shelter.BLL.MasterEntry;
namespace Shelter.UI.MasterEntry
{
public partial class EmployeeCategoryUI : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
LoadDataIntoListBox();
}
else
{
if (listEmployeeCategory.SelectedIndex != -1)
{
LoadDataIntoTextBox(Convert.ToInt32(listEmployeeCategory.SelectedValue));
}
}
}
private void LoadDataIntoTextBox(int val)
{
EmployeeCategory objEmployeeCategory = new EmployeeCategory();
EmployeeCategoryBLL empCategoryBLL = new EmployeeCategoryBLL();
objEmployeeCategory.ID = Convert.ToInt32(val);
DataTable EmpCategoryDt = new DataTable();
EmpCategoryDt = empCategoryBLL.RetrieveById(objEmployeeCategory);
txtEmpCategoryName.Text = EmpCategoryDt.Rows[0]["EmpCategoryName"].ToString();
}
private void LoadDataIntoListBox()
{
EmployeeCategory objEmployeeCategory = new EmployeeCategory();
EmployeeCategoryBLL empCategoryBLL = new EmployeeCategoryBLL();
DataSet EmployeeCategoryDs = new DataSet();
EmployeeCategoryDs = empCategoryBLL.RetreiveFromTable();
DataTable EmployeeCategoryDt = EmployeeCategoryDs.Tables[0];
DataRow tempRow = null;
foreach (DataRow tempRow_Variable in EmployeeCategoryDt.Rows)
{
tempRow = tempRow_Variable;
string rowText = tempRow["EmpCategoryName"] + "(" + tempRow["ID"] + ")";
string rowValue = tempRow["ID"].ToString();
listEmployeeCategory.Items.Add(new ListItem(rowText, rowValue));
}
}
protected void btnSave_Click(object sender, EventArgs e)
{
EmployeeCategory objEmployeeCategory = new EmployeeCategory();
EmployeeCategoryBLL empCategoryBLL = new EmployeeCategoryBLL();
objEmployeeCategory.EmpCategoryName = txtEmpCategoryName.Text;
bool isSave = empCategoryBLL.SaveToTable(objEmployeeCategory);
if (isSave)
{
int id = empCategoryBLL.ReturnLastInsertedId();
lblMessage.Visible = true;
lblMessage.Style.Add("Color", "Green");
lblMessage.Text = "Data saved successfully!";
string rowText = txtEmpCategoryName.Text + "(" +id.ToString()+ ")" ;
string rowValue = id.ToString();
listEmployeeCategory.Items.Add(new ListItem(rowText, rowValue));
txtEmpCategoryName.Text = "";
}
else
{
lblMessage.Visible = true;
lblMessage.Style.Add("Color", "Red");
lblMessage.Text = "Data saving failed!";
}
}
protected void btnEdit_Click(object sender, EventArgs e)
{
if (IsPostBack)
{
EmployeeCategory objEmployeeCategory = new EmployeeCategory();
EmployeeCategoryBLL empCategoryBLL = new EmployeeCategoryBLL();
objEmployeeCategory.EmpCategoryName = txtEmpCategoryName.Text;
objEmployeeCategory.ID = Convert.ToInt32(listEmployeeCategory.SelectedValue);
bool isEdit = empCategoryBLL.EditInTable(objEmployeeCategory);
if (isEdit)
{
int id = objEmployeeCategory.ID;
lblMessage.Visible = true;
lblMessage.Style.Add("Color", "Green");
lblMessage.Text = "Data edited successfully!";
}
else
{
lblMessage.Visible = true;
lblMessage.Style.Add("Color", "Red");
lblMessage.Text = "Data editing failed!";
}
}
}
protected void btnDelete_Click(object sender, EventArgs e)
{
if (IsPostBack)
{
EmployeeCategory objEmployeeCategory = new EmployeeCategory();
EmployeeCategoryBLL empCategoryBLL = new EmployeeCategoryBLL();
objEmployeeCategory.ID = Convert.ToInt32(listEmployeeCategory.SelectedValue);
bool isDelete = empCategoryBLL.DeleteFromTable(objEmployeeCategory);
if (isDelete)
{
lblMessage.Visible = true;
lblMessage.Style.Add("Color", "Green");
lblMessage.Text = "Data deleted successfully!";
listEmployeeCategory.Items.Remove(new ListItem(listEmployeeCategory.SelectedItem.Text, listEmployeeCategory.SelectedValue));
txtEmpCategoryName.Text = "";
}
else
{
lblMessage.Visible = true;
lblMessage.Style.Add("Color", "Red");
lblMessage.Text = "Data deleting failed!";
}
}
}
}
}
txtEmpCategoryName.Text仍然包含旧值，因此每当我尝试更新时，它只会使用旧值而不是文本框中的修改值。似乎TextChanged事件无法正常工作。这个问题的解决方法是什么？
答案 0 :(得分：2)
您可以在Visual Studio中使用实体框架;
选择用于填充列表框并更新说明的商店程序，然后单击“完成”。
CREATE PROCEDURE Proc_name AS BEGIN SET NOCOUNT ON;
CREATE PROCEDURE [dbo]。[UpdateEmpCategoryBLL] @ID int，@ Description varchar（50）AS BEGIN 设置NOCOUNT ON; 更新问题1 SET描述= @Description WHERE ID = @ID END
在您的班级中实施填充列表框和更新说明的方法
公共类包装器 { public static List EmployeeCategory（） { 尝试 { 返回新的LOOKUPEntities（）。empCategoryBLL（）。ToList（）; } catch（例外） { 扔; } }
public static void UpdateEmpCategory(int id, string description)
{
try
{
using (LOOKUPEntities client = new LOOKUPEntities())
{
client.UpdateEmpCategoryBLL(id, description);
}
}
catch (Exception)
{
throw;
}
}
}
protected void Page_Load（object sender，EventArgs e） { if（！Page.IsPostBack） { BindListBox（）; } }
protected void BindListBox（） { 尝试 { ListItem lstBox; listEmployeeCategory.Items.Clear（）; var query = Wrapper.EmployeeCategory（）; foreach（查询中的var项） { lstBox = new ListItem（items.Description，items.ID.ToString（））; listEmployeeCategory.Items.Add（lstBox）; } } catch（Exception ex） { lblMessage.Visible = true; lblMessage.Style.Add（“Color”，“Red”）; lblMessage.Text =“数据加载失败”+ ex +“！”; } }
protected void listEmployeeCategory_SelectedIndexChanged(object sender, EventArgs e)
{
lblMessage.Visible = false;
try
{
Session["ID"] = listEmployeeCategory.SelectedValue.ToString();
txtEmpCategoryName.Text = listEmployeeCategory.SelectedItem.ToString();
}
catch (Exception ex)
{
lblMessage.Visible = true;
lblMessage.Style.Add("Color", "Red");
lblMessage.Text = "Loading session data failed " + ex + " !";
}
}
protected void btnEdit_Click(object sender, EventArgs e)
{
try
{
int id = int.Parse(Session["ID"].ToString());
Wrapper.UpdateEmpCategory(id, txtEmpCategoryName.Text.Trim());
lblMessage.Visible = true;
lblMessage.Style.Add("Color", "Green");
lblMessage.Text = "Data edited successfully!";
BindListBox();
txtEmpCategoryName.Text = string.Empty;
}
catch
{
lblMessage.Visible = true;
lblMessage.Style.Add("Color", "Red");
lblMessage.Text = "Data editing failed!";
}
}
完成！