How to get the value of html <input type="hidden"> in PHP?

Question

I am a certifid newbie so pls be patient with me if my question might sound very idiotic to you.

Hi guys. Im trying to get the value of an html <input type="hidden"> using PHP. The value of that hidden element is passed from Javascript and I need to display the value of that hidden element by using php echo. From what I understand (I hope I understood it right) when you do something like $description = isset($_GET['description']) ? $_GET['description'] : null; and also <input type="hidden" id="description" value="<?php echo $description; ?>" /> you can access/display the value of the hidden element by using <?php echo $_GET['description']; ?> but I am getting an undefined index: description. I am a total noob so I am really confused about this. I hope my question is not that confusing. Anyway I am very willing to answer probing questions.

BTW, here are the codes:

index.php

<?php include('functions.php'); ?>

<?php 
 $yr = isset($_GET['year_list']) ? $_GET['year_list'] : null;
 $evnt = isset($_GET['event_list']) ? $_GET['event_list'] : null; 
 $description = isset($_GET['description']) ? $_GET['description'] : null; 
?>

<html>
<head>
 <script type="text/javascript" src="myscripts.js"></script>
 <style type='text/css'>
  #show_description {
   min-height: 100px;
   min-width: 500px;
   max-height: 100px;
   max-width: 500px;
   background-color: #000;
   color: #fff;
   padding: 10px;
  }
 </style>
</head>
<body onload="check_year_event();">
 <div>
  <form name="myform" action="index.php" method="get" >
   <input type="hidden" id="hidden_year_list" value="<?php echo $yr; ?>" />
   <input type="hidden" id="hidden_event_list" value="<?php echo $evnt; ?>" />
   <input type="hidden" id="description" value="<?php echo $description; ?>" />

   Select Year: <?php echo hspacer(1); ?>
   <select id="year_list" name="year_list" onchange="check_year_event();" >
   <?php  
    for($year = (date('Y') - 100); $year <= (date('Y') + 100); $year++ ) {
     if ($year == date('Y'))  echo "<option value='$year' name='$year' selected='' >" . $year . "</option>";
     else echo "<option value='$year' name='$year' >" . $year . "</option>";
    }
   ?>
   </select>
   <?php echo hspacer(5); ?>
   Select Event:  <?php echo hspacer(1); ?>
   <select id="event_list" name="event_list" onchange="check_year_event();" >
   <?php  
    $events = array("Karate Tournament", "Beauty Pageant", "Film Festival", "Singing Contest", "Wedding");

    foreach($events as $event) echo "<option value='$event' name='$event' >" . $event . "</option>";
   ?>
   </select>
   <?php echo vspacer(2); echo hspacer(22); ?>
   <input type="submit" id="send_notice" value="Send Notice" onclick="check_year_event(); return false; "/> 
  </form>
 </div>

 <div id="show_description" >
  <?php echo $_GET['description']; ?>
 </div>

</div>
</body>
</html>

functions.php

<?php
 function hspacer($num_of_spaces) {
  $spaces = "";
  if ($num_of_spaces > 0)  for($i=0; $i<$num_of_spaces; $i++ )  $spaces .= "&nbsp;";

  return $spaces;
 }

 function vspacer($num_of_linefeeds) {
  $linefeeds = "";
  if ($num_of_linefeeds > 0)  for($i=0; $i<$num_of_linefeeds; $i++ )  $linefeeds .= "<br />";

  return $linefeeds;
 }
?>

myscripts.js

function create2DArray(row, col){
 var array2D = new Array(row);

 for (var i = 0; i < row; i++) {
  array2D[i] = new Array(col);
 }

 return array2D;
}


function check_year_event() {
 var years_and_events = create2DArray(10, 3);


 years_and_events[0][0] = 2001; 
 years_and_events[0][1] = "Karate Tournament"; 
 years_and_events[0][2] = "Annual karate tournament held globally"; 
 years_and_events[1][0] = 2002; 
 years_and_events[1][1] = "Beauty Pageant"; 
 years_and_events[1][2] = "Beauty pageant held globally"; 
 years_and_events[2][0] = 2003; 
 years_and_events[2][1] = "Film Festival"; 
 years_and_events[2][2] = "Film festival held globally"; 
 years_and_events[3][0] = 2004; 
 years_and_events[3][1] = "Singing Contest"; 
 years_and_events[3][2] = "Singing contest tournament held globally"; 
 years_and_events[4][0] = 2005; 
 years_and_events[4][1] = "Wedding"; 
 years_and_events[4][2] = "Wedding tournament held globally"; 
 years_and_events[5][0] = 2007; 
 years_and_events[5][1] = "Karate Tournament"; 
 years_and_events[5][2] = "Annual karate tournament held globally"; 
 years_and_events[6][0] = 2008; 
 years_and_events[6][1] = "Beaty Pageant"; 
 years_and_events[6][2] = "Beauty pageant held globally"; 
 years_and_events[7][0] = 2009; 
 years_and_events[7][1] = "Film Festival"; 
 years_and_events[7][2] = "Film festival held globally"; 
 years_and_events[8][0] = 2010; 
 years_and_events[8][1] = "Singing Contest"; 
 years_and_events[8][2] = "Singing contest tournament held globally"; 
 years_and_events[9][0] = 2011; 
 years_and_events[9][1] = "Wedding"; 
 years_and_events[9][2] = "Wedding tournament held globally"; 


 var year = document.getElementById('year_list').value;
 var event = document.getElementById('event_list').value;
 var found = false;

 for (var i = 0; i < years_and_events.length; i++) {
  if ((year == years_and_events[i][0]) && (event == years_and_events[i][1])) {
    document.getElementById('description').value = years_and_events[i][2];
    document.getElementById('send_notice').style.visibility = "hidden";
    document.getElementById('show_description').style.visibility = "visible";
    found = true;
    break;
   }
  }

 if (found == false) {
  document.getElementById('show_description').style.visibility = "hidden";
  document.getElementById('send_notice').style.visibility = "visible";
 }
}

Chris Bornhoft · Accepted Answer · 2011-05-15 05:20:31Z

2

You need to give the input a name. So:

<input name="description" />

answered May 15, 2011 at 5:20

Chris Bornhoft

4,3095 gold badges40 silver badges56 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Newbie Coder Over a year ago

is it OK to have the ID as well?

Mauvis Ledford Over a year ago

It doesn't need an id attribute - that's just for CSS or JavaScript. Name is what's needed for the server.

score 1 · Accepted Answer · 2011-05-15 06:04:59Z

1

Inside the show_description div replace $_GET['description'] with $description.

EDIT: I think I understand why you are confused now. If you want to display the value of the description input in the show_description div, you need to use javascript to do that. PHP is server side and it only runs once, when the page is requested by the browser. If you are doing anything that happens after the page is loaded, you need to use javascript. That said, make this change to your check_year_event() function.

 for (var i = 0; i < years_and_events.length; i++) {
  if ((year == years_and_events[i][0]) && (event == years_and_events[i][1])) {
    document.getElementById('description').value = years_and_events[i][2];
    document.getElementById('show_description').innerHTML = years_and_events[i][2];
    document.getElementById('send_notice').style.visibility = "hidden";
    document.getElementById('show_description').style.visibility = "visible";
    found = true;
    break;
  }
 }

And remove the echo $_GET['description'] from the index.php file

edited May 15, 2011 at 6:04

answered May 15, 2011 at 5:59

user752897

5 Comments

Newbie Coder Over a year ago

I just changed it to <?php echo $description; ?> but it doesn't show anything. It seems that the $description is an empty variable. How is it possible?

user752897 Over a year ago

I think I got what you need now.

Newbie Coder Over a year ago

OMG... It worked!!! BTW, what is innerHTML??? Is that what made it work??? Can tell me what is that???

user752897 Over a year ago

innerHTML is the javascript property of an element that specifies all the text inside of it. Mozilla - innerHTML

RobG Over a year ago

@exahex - innerHTML is a DOM property, it should be provided by any language implementing the W3C HTML5 draft, not just javascript.

tlunter · Accepted Answer · 2011-05-15 05:21:55Z

1

You would need to set the name of the <input type="hidden"> like <input type="hidden" name="hiddenfield">

Then you can reference this field in the PHP by $_GET['hiddenfield']. Make sure the input is in the form.

answered May 15, 2011 at 5:21

tlunter

7241 gold badge5 silver badges14 bronze badges

Comments

Denis de Bernardy · Accepted Answer · 2011-05-15 05:26:28Z

1

You need to give your input a name, an id or both: <input type="hidden" id="foo">

A few side notes...

There's a very useful javascript library that you might want to try:

http://jquery.com/

It comes with multitudes of UI elements and plugins, and allows to do many things in a much simpler way than what you're currently writing.

You might also want to document yourself a bit on SQL injections, cross-site scripting and cross-site request forgery. A lot of stuff needs to be escaped in your code.

answered May 15, 2011 at 5:26

Denis de Bernardy

79.2k14 gold badges138 silver badges158 bronze badges

4 Comments

Newbie Coder Over a year ago

I did something like <input type="hidden" id="description" name="description" value="<?php echo $description; ?>" and then <?php echo $_GET['description']; ?>, still having the same error

Denis de Bernardy Over a year ago

That's because you've another field with the same name or id.

Denis de Bernardy Over a year ago

My bad, I had only scanned your code. Your description field is missing a name; without it, it won't be sent for use by $_GET. I'm suspecting that your undefined index is a php notice that comes from <?php echo $_GET['description']; ?>. It should likely be <?php echo $description; ?>.

Newbie Coder Over a year ago

I just changed it to <?php echo $description; ?> but it doesn't show anything. It seems that the $description is an empty variable. How is it possible?

Collectives™ on Stack Overflow

How to get the value of html <input type="hidden"> in PHP?

4 Answers 4

2 Comments

5 Comments

Comments

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

5 Comments

Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related