How do I pass an HTML element's value to a C# code-behind method?
Question
For example, right now I have my ASPX like so:
<form name="form" runat="server" onsubmit="validate(this)">
<table width="100%" height="100%">
<tr>
<td class="label">
Start Date:
</td>
<td>
<input type="text" name="StartDate" value='<%=GetCurrentDate("- testParam")%>' maxlength="10" />
</td>
</tr>
</table>
</form>
..and my C# as follows:
public static string GetCurrentDate(string str)
{
return DateTime.Now.ToString("MM/dd/yyyy") + str;
}
This works fine and outputs "03/08/2017 - testParam". But what if, for example, instead of sending a hardcoded string manually as I did above, I want to pass in one of the HTML element's values as a parameter from the ASPX side? Like this:
...
<tr>
<td class="label">
Start Date:
</td>
<td>
<input type="text" name="StartDate" value="<%=GetCurrentDate(formObj.elements.item('someLabel').value)%>" maxlength="10" />
</td>
</tr>
...
What do I need to do to get the "someLabel" element's value on my ASPX page to the C# page? Any help with this will be greatly appreciated.
4 answers
solution1
1 2017-03-08 18:29:06
this method GetCurrentDate running server side but this formObj.elements.item('someLabel').value running on client
try this..
<tr>
<td class="label">
Start Date:
</td>
<td>
<input type="text" name="StartDate" value='<%=GetCurrentDate()%>' maxlength="10" />
</td>
public string GetCurrentDate()
{
return DateTime.Now.ToString("MM/dd/yyyy");
}
for read value of input named as StartDate from server..
string postValue = Request.Form["StartDate"]
solution2
1 ACCPTED 2017-03-08 18:51:59
If you want to pass a value from client-side to code behind without posting back the entire page , you will need to use Ajax.
Calling to a server-side method in ASP.Net Web Form is not as clean as ASP.Net Web API or MVC. You will need to use old WebMethod .
For example,
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="DemoWebForm.Default" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<button type="button" onclick="getData();">Get Data</button>
<br/>
<input type="text" name="StartDate" id="txtStartDate" maxlength="10" />
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script type="text/javascript">
function getData() {
var data = {value: "test"};
$.ajax({
type: "POST",
url: '<%= ResolveUrl("~/Default.aspx/GetCurrentDate") %>',
data: JSON.stringify(data),
contentType: "application/json",
success: function (msg) {
$("#txtStartDate").val(msg.d);
}
});
}
</script>
</form>
</body>
</html>
Code Behind
using System;
using System.Web.Script.Serialization;
namespace DemoWebForm
{
public partial class Default : System.Web.UI.Page
{
[System.Web.Services.WebMethod]
public static string GetCurrentDate(string value)
{
return new JavaScriptSerializer().Serialize(
string.Format("{0} - {1}", DateTime.Now, value));
}
}
}
solution3
1 2017-03-08 19:17:22
You can make it a server control by adding runat="server" and it will be available in your code behind file. OR if you don't prefer this then use Request.Form["Name"] in your code behind file. Here "Name" is the name you are giving to your textbox control.
In your case the name is StartDate
So try to access the value of textbox from the code behind using Request.Form["StartDate"]
Read this article.. https://www.aspsnippets.com/Articles/Get-value-of-HTML-Input-TextBox-in-ASPNet-code-behind-using-C-and-VBNet.aspx
solution4
0 2017-03-08 18:26:37
您应该将要发送到Web服务器的值以html形式发布。
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