Develop Reference

Override asp net web form action

I have the following web form:
Working Form:
<form id="transactionParameters" method="post" runat="server" action="remote_url.aspx">
<fieldset>
<p>
<label for="Username">Username:</label>
<asp:TextBox id="Username" Text="TomSelleck" runat="server" />
</p>
<asp:Button ID="SubmitForm" runat="server" onclick="SubmitForm_Click" Text="Button" />
</fieldset>
</form>
And this successfully submits the form value Username to remote_url.aspx and brings the user to the remote page.
The problem I face is that I need to add a value to the form before submitting the form and redirecting the user e.g:
Desired functionality:
<form id="transactionParameters" method="post" runat="server">
<fieldset>
<p>
<label for="Username">Username:</label>
<asp:TextBox id="Username" Text="TomSelleck" runat="server" />
</p>
<asp:Button ID="SubmitForm" runat="server" onclick="SubmitForm_Click" Text="Button" />
</fieldset>
</form>
// This method is fired but I don't know how to execute the commented out code
protected void SubmitForm_Click(object sender, EventArgs e)
{
// Form["Username"] = Username.Text.Uppercase();
// Form["NewValue"] = DateTime.Now.ToString();
// ExecuteAction(Form, "remote_url.aspx");
}

You can accomplish this in several different ways.
Query String
Session
Cookie
Internal variable / object
The question will be what are the requirements? The easiest would be the Query String, simply do Response.Redirect("...aspx?username=Tom");.
Then on the other form you would simply parse the Query String. Request.QueryString["username"]?.ToString().
The drawback would be your url has a username in clear text and is exposed easily. The Session would store a unique identifier of that information into a cookie, making those approaches similar. But equally easy and may meet your requirements.
An internal object variable after the method fires, storing that object in memory making it accessible and exposed on the other page load event will work also.

prevent Asp.NET button from submitting form

So, I have a Paypal form that worked wonders. However, I now need to add a coupon field, where someone can enter a code, and get a reduction based on whatever the backend replies.
This all works wonderfully, but I've ran into an issue when adding the option to know before checking out whether your code is valid or not. Currently, my form (once simplified) looks like this :
<form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post"
id="payPalForm" runat="server">
<asp:TextBox runat="server" ID="txtCode" />
<asp:Button Text="Validate" OnClick="ValidateDiscount" runat="server" />
<asp:Label ID="txtDesc" runat="server" />
<input type="submit" name="Submit" value="Pay up!" />
<input type="hidden" name="cmd" value="_cart" />
<input type="hidden" name="upload" value="1" />
...
</form>
With the backend having the function :
protected void ValidateDiscount(object sender, EventArgs e)
{
this.txtDesc.Text = "fetch from database using: " + txtCode.Text;
}
My issue is that wheneve I click on the Validate button, the form is submitted and I end up on the Paypal website. I used Jquery at first with preventDefault(), but that actually prevents my server-side function from firing. I've also tried putting a standard <button> or <input type='button'> tag instead, but I couldn't get it to fire my server-side function.
Is there any way to have the Validate button not submit the form, or should I just remove the action from the form and manually submit the form when clicking on the submit button?

You have set your form action to post to PayPal.
This is the action:
action="https://www.sandbox.paypal.com/cgi-bin/webscr"
Here is where you have it in you form tag:
<form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post"
id="payPalForm" runat="server">
Remove this from your form tag and it should postback to your application.

onsubmit function wont fire while having a runat=server attribute

<%# Page Language="C#" AutoEventWireup="true" CodeFile="Register.aspx.cs" Inherits="Register" MasterPageFile="MasterPage.master" %>
<asp:Content ID="ContentPlaceHolder1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
</asp:Content>
<asp:Content ID="ContentPlaceHolder2" ContentPlaceHolderID="ContentPlaceHolder2" Runat="Server">
<br />
<div id="signupform">
<form class="signupform" name="formreg" runat="server" onsubmit="return valform()"> <br/>
<input dir="rtl" type="text" name="uname" class="uname"/> </br>
<input dir="rtl" type="text" name="fname" class="fname"/> </br>
<input dir="rtl" type="text" name="lname" class="lname"/> </br>
<input dir="rtl" type="password" name="pword" class="pword"/> </br>
<input dir="rtl" type="password" name="rpword" class="rpword"/> </br>
<input dir="rtl" type="text" name="mmail" class="mail"/> </br>
<input dir="rtl" type="text" name="rmail" class="rmail"/> </br>
<input dir="rtl" type="text" name="gil" class="gil"/> </br>
<input type="checkbox" name="anon" value="True" class="dropan"/></br>
<input type="submit" name="sub" class="subbutton" value=""/>
<%=registrationstatus %>
</form>
</div>
</asp:Content>
This is my code, My problem is that the onsubmit="return valform()" attribute on my form wont fire if the runat="server" attribute exists, they can't work together please help me I am clueless why these two attributes wont work together

This is because you can't use both together. As said in the docs -
<input type="text" id="Textbox1" runat="server">
Doing this will give you programmatic access to the HTML element on the server before the Web page is created and sent down to the client. The HTML element must contain an id attribute. This attribute serves as an identity for the element and enables you to program to elements by their specific IDs. In addition to this attribute, the HTML element must contain runat="server". This tells the processing server that the tag is processed on the server and is not to be considered a traditional HTML element.
Here is the reference.
http://msdn.microsoft.com/en-us/library/aa478973.aspx
under section - Using HTML Server Controls
So, HTML with run='server' will not be treated as a normal Html element and thus will always be processed by the server. If you want to override the default behavior, you have to bind your javascripts with after the html is loaded in the browser, may be using jQuery or something similar. With jQuery something like this would help -
$(function(){
$("#formreg").submit(function(){
return valform();
});
});

By examing your code, I reach on conclusion that you might be using another form tag on Master page and there is no javascript issue. Only one form tag(Server Side) can exists either on a master page or content page. They can not be nested. When you would use runat="Server" attribute on both of form tags then error occurs saying "A page can have only one server-side Form tag". So remove runat="server" attribute from one of the form tags, onsubmit would begin firing.

I solved it with very easy way.
if we have such a form
<form method="post" name="setting-form" >
<input type="text" id="UserName" name="UserName" value=""
placeholder="user name" >
<input type="password" id="Password" name="password" value="" placeholder="password" >
<div id="remember" class="checkbox">
<label>remember me</label>
<asp:CheckBox ID="RememberMe" runat="server" />
</div>
<input type="submit" value="login" id="login-btn"/>
</form>
You can now catch get that event before the form postback and stop it from postback and do all the ajax you want using this jquery.
$(document).ready(function () {
$("#login-btn").click(function (event) {
event.preventDefault();
alert("do what ever you want");
});
});

asp.net can't take the text of input text

This is my aspx
<p>Date: <input type="text" id="datepicker" >
<asp:Button id="BookingForDate" runat="server" OnClick="BookingForDate_Click" Text="Search"/> </p>
<table id="DateBookingTable" runat="server" style="visibility:hidden">
<tr><th>ID</th><th>PlanTime</th></tr>
</table>
on my code in c# I can't see datepicker
why?
note please that i can take all the controllers from id except this one.
I already tried restart the visual studio

You have 2 options
add runat="server" to the input
<input type="text" id="datepicker" runat="server" />
or create an TextBox
<asp:TextBox runat="server" id="datepicker"></asp:TextBox>

You should add
runat="server"
to your input. No you are using an html control and not an asp.net server side control. Hence you can't access the value of the textbox the way you want.
So try the following and then you will be able to access the value of your textbox:
<asp:TextBox id="datepicker" runat="server"/>
Then in your code behind class you can access the value of this textbox
datepicker.Text
Another approach, as I pointed initially, it would be the following:
<input type="text" id="datepicker" runat="server">

You forgot to add the runat-attribute to your input-tag. Try this:
<input type="text" id="datepicker" runat="server">
With that change, you should be able to access the element from code behind
See MSDN

You have not given name to your control and also add runat="server"
<input type="text" id="datepicker" runat="server" name='datepicker' />

adding text to legend from code behind

how can i add text to a legend from code behind

Assuming you're talking about the HTML Legend Tag and using C# in an ASP.NET site. You can give it an ID and a runat="server" then you can access it from the code behind by name and change its text property.
<form id="form1" runat="server">
<fieldset>
<legend id="myLegend" runat="server">Personalia:</legend>
Name: <input type="text" size="30" /><br />
Email: <input type="text" size="30" /><br />
Date of birth: <input type="text" size="10" />
</fieldset>
</form>
Then in the code behind:
myLegend.InnerText = "Foo";