C# Posting form from JavaScript to another .aspx but no parameters in Params

user_5056011 0
Viewed 571

In an .aspx page I'm filling out a number of hidden form fields with JavaScript and then want to post the form to another .aspx page. It submits the form properly but when I look at the Request.Params["org"] in the page that was called in the form's action it's null.

<script src="prototype.js"></script>
<script>
function doIt() {
    $('org').value = org_int;
    $('frmCheckout').submit();
}
</script>
...
<form id="frmCheckout" method="post" action="checkout.aspx">
<input type="hidden" value="" id="org" name="org">
<input type="submit" onclick="doIt()" value="Submit">
</form>

$ is the prototype notation which was brought in before the example. $ in prototype is the same as document.getElementById('frmCheckout').

MAJOR EDIT 2/1/2021 7:52: Looking for the solution I found a couple of new bits of information but it still doesn't work.

I found PostBackUrl which will change the .aspx's action to another .aspx page. This part works. When submitted, it calls Checkout.aspx

<asp:Button ID="Submit" PostBackUrl="Checkout.aspx" runat="server" Text="Submit" />

But the data is not available in Checkout.aspx... there are no values in Request.Form (which there is supposed to be) or Request.Params.
I've also tried:

<asp:TextBox runat="server" name="jsonString" id="jsonString" value="js" />

But I'm getting an invalid __VIEWSTATE I know I'm supposed to change it but nothing has worked yet.

form-submit c#
4 Answers

Try the following. In the following example the Javascript needs to be after the form code. Request.Form["org"] is used to get the value of "org" from the posted data. Also, if one uses $ in Javascript, it's important not to use it until it's defined. See javascript dollar sign variable not working.

Test.aspx (works)

<!-- directives -->
<% @Page Language="C#" %>

<html>
   <head> 
      <title> Test Form </title> 
   </head>
   
   <body>
      <h3> Test Form </h3>

      <form runat="server" id="frmCheckout" method="post" action="checkout.aspx">
         <input runat="server" type="hidden" id="org" name="org" value=""/>
         
      </form>

      <script>
          function setInitialVals() {
              document.getElementById('org').value = "3";
              document.getElementById('frmCheckout').submit();
          };

          setInitialVals();
      </script>
   </body>
</html>

checkout.aspx

<!-- directives -->
<% @Page Language="C#" %>

<html>
   <head> 
      <title> Checkout</title> 
   </head>
   
   <body>
      <h3> Checkout </h3>
      
       <% Response.Write("org: " + Request.Form["org"]); %>  
      
   </body>
</html>

The following won't work:

Test.aspx (doesn't work)

Note: The following won't work because the Javascript is executed before the input element is rendered.

<!-- directives -->
<% @Page Language="C#" %>

<html>
   <head> 
      <title> Test Form </title> 
   </head>
   
   <body>
      <h3> Test Form </h3>

      <script>
          function setInitialVals() {
              document.getElementById('org').value = "3";
              document.getElementById('frmCheckout').submit();
          };

          setInitialVals();
      </script>

      <form runat="server" id="frmCheckout" method="post" action="checkout.aspx">
         <input runat="server" type="hidden" id="org" name="org" value=""/>
         
      </form>
   </body>
</html>

Resources

Introducing ASP.NET Web Pages - HTML Form Basics

user_100244250

Please, change the approach. Consider add an asp button into the form and fire click event for this button; the button properties need to be like this topic of Microsoft Docs How to: Post ASP.NET Web Pages to a Different Page:

<script src="prototype.js"></script>
<script>
function doIt() {
    $('#org').value = org_int;
    $('#btnPostBack').click();
}
</script>
...
<form id="frmCheckout" method="post">
<input type="hidden" value="" id="org" name="org">
<input type="button" onclick="doIt()" value="Submit">
<asp:Button ID="btnPostBack" ClientIdMode="Static" PostBackUrl="~/checkout.aspx"  runat="server" Text="Post Form To Another Page" style="display:none;"/>
</form>

Note: I saw in your code that id's selectors not contains hashtag prefixes in your JS code...

user_105497910

Please,

try change form method attribute from post to get, if you want use "org" as Query String:

$('org').value = org_int;
$('frmCheckout').submit();
...
<form id="frmCheckout" method="get" action="checkout.aspx">
<input type="hidden" value="" id="org" name="org">
</form>
user_105497910

Update:

I downloaded prototype.js and added it to the test code below which seems to work. The only difference between the code you posted and the code below should be that I hard-coded the value of "org_int" in function "doIt": let org_int = 3;.

test.aspx

<% @Page Language="C#" %>

<html>
   <head> 
      <title> Test Form </title> 
   </head>
   
   <body>
      <h3> Test Form </h3>

       <script src="prototype.js"></script>
             
       <script>
           function doIt() {

               try {
                        let org_int = 3;

                        $('org').value = org_int;
                        $('frmCheckout').submit();

                        //document.getElementById('org').value = org_int;
                        //document.getElementById('frmCheckout').submit();
               }
               catch (err) {
                   console.log(err);
                   alert(err);       
               }
           }

       </script>

        <form id="frmCheckout" method="post" action="checkout.aspx">
            <input type="hidden" value="" id="org" name="org">
            <input type="submit" onclick="doIt()" value="Submit">
        </form>
       
   </body>
</html>

checkout.aspx

<% @Page Language="C#" %>

<html>
   <head> 
      <title> Checkout</title> 
   </head>
   
   <body>
      <h3> Checkout </h3>
      
       <% Response.Write("Request.Form[\"org\"]: " + Request.Form["org"] + "<BR>"); %>  
       <% Response.Write("Request.Params[\"org\"]: " + Request.Params["org"]); %>  
      
   </body>
   
</html>
user_100244250
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