title: How can i know specific value on a form using `request.form`?
body: <p>How can i know specific value on a form using <code>request.form</code>?
  I am trying it long but no success.</p>
  
  <pre><code>i want to check something like this
  if (request.form.contains("text_check"))  //But it doesn't work
  {
  go in;
  
  }
  else{
  
  here we go;
  }
  </code></pre>
  
  <p>i want to know specific value from AllKeys, and total count of all keys too.</p>