javascript - 如何从 ASP.NET 中的前端 Javascript 函数调用后端 C# 函数

Question

我目前正在从事 C# 和 Asp.net 的无薪实习。我的雇主要求我编写一个 javascript 函数，以便在删除记录之前告诉用户他们是否确定要从数据库中删除记录。

经过一些研究后，我能够编写出 Javascript 函数来告诉用户他们是否确定要删除这条记录，然后再从数据库中实际删除它。

javascript 函数有效。但是现在我遇到了如何调用后端 C# 函数的问题，该函数实际上会从我刚刚编写的前端 javascript 函数中删除数据库中的记录？

这是我的代码:

Javascript 函数:

function watchdelete() 
{
    if (confirm("Are you Sure You want to delete this Manufacturer?") == true)
   {
        __doPostBack('btnDelete_Click','');//"PageMethods.btnDelete_Click();
   }
    else { }
}

调用附加到删除按钮的 javascript 客户端代码的前端部分:

<asp:Button ID="btnDelete" runat="server" Text="Delete" OnClientClick=" return watchdelete()" OnClick="btnDelete_Click1" />

为了从数据库中删除记录而调用的后端 C# 函数:(请注意，只要调用此函数并执行，我就会很高兴，您不必担心关于它的内部运作的太多了。谢谢)

protected void btnDelete_Click(object sender, EventArgs e)
{
    String com, command, findmodel;

    if (txtManufactureName.Text != "")                                      // If the manufacturer name is not null
    {
        if (txtManufactureName.Text == grdManufact.SelectedRow.Cells[1].Text) // And the manufacturer name must not be
        {                                                                     // Changed from selected one
            string strConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString2"].ToString();
            try
            {
                using (SqlConnection conn = new SqlConnection(strConnectionString))
                {
                    conn.Open();                                               // Connect to database
                    String moderated = (checkBoxModerated.Checked) ? "true" : "false";
                    findmodel = "SELECT * From VehicleModels WHERE ManufacturerID = '" + txtManID.Text + "';"; 
                    com = "SELECT * From VehicleManufacturer WHERE ManufacturerName = '" + txtManufactureName.Text + "' AND Ismoderated ='" + moderated + "';";
                    command = "DELETE From VehicleManufacturer WHERE ManufacturerName = '" + txtManufactureName.Text + "' AND Ismoderated ='" + moderated + "';";
                    SqlDataAdapter finder = new SqlDataAdapter(findmodel, conn);
                    DataTable dat = new DataTable();
                    int nummods = finder.Fill(dat);
                    if (nummods == 0)
                    {
                        SqlDataAdapter adpt = new SqlDataAdapter(com, conn);
                        DataTable dt = new DataTable();
                        int number = adpt.Fill(dt);                                // try to find record to delete
                        if (number == 0)                            // If there is no such record to delete
                        {                                           // Indicate this to user with error message
                            txtMessage.Text = "Sorry, there is no such record to delete";
                        }
                        else
                        {                                           // Otherwise delete the record
                            using (SqlCommand sequelCommand = new SqlCommand(command, conn))
                            {
                                sequelCommand.ExecuteNonQuery();
                                txtMessage.Text = "Manufacturer Deleted Successfully";
                                txtManufactureName.Text = "";       // Reset manufacturer name
                                txtDescription.Text = "";           // Reset Description
                                checkBoxModerated.Checked = false;  // clear moderated checkbox
                            }
                        }
                    }
                    else
                    {
                        txtMessage.Text = "Sorry. You must delete associated models first.";
                    }
                    conn.Close();                               // Close the database connection. Disconnect.
                }
                BindGrid();                                     // Bind Manufacturer Grid again to redisplay new status.
            }
            catch (SystemException ex)
            {
                txtMessage.Text = string.Format("An error occurred: {0}", ex.Message);
            }
        }
        else
        {
            txtMessage.Text = "Sorry. You cant change the manufacturer name before deleting";
        }
    }
    else
    {   // Otherwise give error message if manufacturer name missing
        txtMessage.Text = "Please enter a manufacturer name to delete";
    }
}

任何想法将不胜感激。

Answer 1

让我们将验证函数简化为:

function confirmDelete(){
  return confirm("Are you Sure You want to delete this Manufacturer?");
}

然后带有 OnClientClick 属性的按钮将类似于

OnClientClick=" return confirmDelete()"  

只要您的验证函数返回 false .NET 就不会将您的代码提交给服务器。