How to check form submission ASP classic

asp-classicformspost

I'm setting up a form in ASP classic and it will reload after submission (action self)

But this time it shows results of previous submissions, so how can I check that a POST submission has been made?

Like in PHP:

if($_POST['submit']) {
  show results...
}

Best Answer

You have several options:

Method 1 - Check the request method:

If Request.ServerVariables("REQUEST_METHOD") = "POST" Then
    'Show Results...
End If

Method 2 - add a hidden field to your form with a value then check if that value has been posted:

If Request.form("HiddenValue") = "1" Then
    'Show Results...
End If

Method 3 - Check if the request.form collection contains items:

If Request.Form.Count > 0 Then
    'Show Results...
End If

Method 4 - Post to a querystring (i.e. set action of <form> to ?post=yes)

If Request.QueryString("post") = "yes" Then
    'Show Results...
End If

Which one to pick?

My preferred option is method 4 – as it’s easily visible in the address bar as to what’s going on – if for some reason I want to avoid presenting this level of detail in the url, I tend to use option 3 as it’s easy to implement, requires no changes on the source forms & is reliable. As for the other two methods:

Method 1 – I tend to avoid relying on server variables if I don’t have 100% control over the server – no real justification for that, just a general habit I tend to work with.
Method 2 – You could substitute a hidden field for another field that will always contain a value.

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/**
 * sends a request to the specified url from a form. this will change the window location.
 * @param {string} path the path to send the post request to
 * @param {object} params the parameters to add to the url
 * @param {string} [method=post] the method to use on the form
 */

function post(path, params, method='post') {

  // The rest of this code assumes you are not using a library.
  // It can be made less verbose if you use one.
  const form = document.createElement('form');
  form.method = method;
  form.action = path;

  for (const key in params) {
    if (params.hasOwnProperty(key)) {
      const hiddenField = document.createElement('input');
      hiddenField.type = 'hidden';
      hiddenField.name = key;
      hiddenField.value = params[key];

      form.appendChild(hiddenField);
    }
  }

  document.body.appendChild(form);
  form.submit();
}

Example:

post('/contact/', {name: 'Johnny Bravo'});

EDIT: Since this has gotten upvoted so much, I'm guessing people will be copy-pasting this a lot. So I added the hasOwnProperty check to fix any inadvertent bugs.

Best Answer

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