C# DropDownList事件未在AutoPostBack设置为true时触发
我的网页中有DropDownList，每次用户更改DropDownList中的选定值时，我都会填充文本框 我的问题是，当我更改此值时，此事件未触发。有趣的是，只有当我更改值并按下按钮时才会触发此事件，这将创建新的请求 我尝试将AutoPostBack值更改为true，尝试更改ViewStateMode，并尝试在textChanged事件上启动此函数。 我还加了条件！isPostBack在数据绑定函数之前C# DropDownList事件未在AutoPostBack设置为true时触发,c#,asp.net,events,C#,Asp.net,Events,我的网页中有DropDownList，每次用户更改DropDownList中的选定值时，我都会填充文本框 我的问题是，当我更改此值时，此事件未触发。有趣的是，只有当我更改值并按下按钮时才会触发此事件，这将创建新的请求 我尝试将AutoPostBack值更改为true，尝试更改ViewStateMode，并尝试在textChanged事件上启动此函数。 我还加了条件！isPostBack在数据绑定函数之前 if (!IsPostBack) { LoadDatabaseContent();
if (!IsPostBack)
{
LoadDatabaseContent();
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
StringBuilder sb = new StringBuilder();
byte[] buf = new byte[8192];
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://localhost:44333/Backend2.aspx?update=true&id=" + DropDownList1.SelectedItem.Text);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Stream resStream = response.GetResponseStream();
int count;
do
{
count = resStream.Read(buf, 0, buf.Length);
if (count != 0)
{
string tempString = Encoding.ASCII.GetString(buf, 0, count);
sb.Append(tempString);
}
}
while (count > 0);
Response.Write(sb.ToString());
//createTextBox.Text = sb.ToString();
resStream.Dispose();
response.Dispose();
}
if (!IsPostBack)
{
LoadDatabaseContent();
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
StringBuilder sb = new StringBuilder();
byte[] buf = new byte[8192];
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://localhost:44333/Backend2.aspx?update=true&id=" + DropDownList1.SelectedItem.Text);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Stream resStream = response.GetResponseStream();
int count;
do
{
count = resStream.Read(buf, 0, buf.Length);
if (count != 0)
{
string tempString = Encoding.ASCII.GetString(buf, 0, count);
sb.Append(tempString);
}
}
while (count > 0);
Response.Write(sb.ToString());
//createTextBox.Text = sb.ToString();
resStream.Dispose();
response.Dispose();
}
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Backend.aspx.cs" Inherits="APIS.Backend" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>
</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Button ID="buttonGeneratePdf" runat="server" OnClick="buttonGeneratePdf_Click" Text="Generate PDF" />
<br />
<asp:Button ID="buttonGenerateQrCode" runat="server" OnClick="buttonGenerateQrCode_Click" Text="Generate QR" />
<br />
</div>
<div>
<asp:DropDownList ID="DropDownList1" runat="server" Width="400px" Height="16px" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged"
OnTextChanged="DropDownList1_TextChanged">
</asp:DropDownList>
</div>
</form>
</body>
</html>
protected void Page_Load(object sender, EventArgs e)
{
string generateQrCode = Request.QueryString["generateqrcode"];
if (generateQrCode != null && generateQrCode == "true") GenerateQrCode();
}
private void GenerateQrCode()
{
string id = Request.QueryString["id"];
QRCodeGenerator qr = new QRCodeGenerator();
QRCodeData data = qr.CreateQrCode(id, QRCodeGenerator.ECCLevel.Q);
QRCode code = new QRCode(data);
Bitmap QRbmp = code.GetGraphic(5);
QRbmp.Save("pathtofile..\\QRcode.jpg");
}
Javascript似乎无法执行，因为表单上不存在元素
\uuu EVENTTARGET\uu EVENTARGUMENT<input type="hidden" name="__EVENTTARGET" id="__EVENTTARGET" value="" />
<input type="hidden" name="__EVENTARGUMENT" id="__EVENTARGUMENT" value="" />
您应该尝试确认这些元素是否正在生成，如果没有，则尝试跟踪它们不存在的原因。您可能需要使用