AJAX Poll in php

AJAX Poll In Php

PHP and AJAX Poll :

AJAX Suggest

In the AJAX example below we will demonstrate a poll where the web page can get the result without reloading.

Do you like PHP and AJAX so far?

This example consists of four pages:

a simple HTML form

a JavaScript

a PHP page

a text file to store the results

HTML Form :

This is the HTML page. It contains a simple HTML form and a link to a JavaScript:

CODE/PROGRAM/EXAMPLE

<html>
<head>
<script src="poll.js"></script>
</head>
<body>
<div id="poll">
<h2>Do you like PHP and AJAX so far?</h2>
<form>
Yes:
<input type="radio" name="vote"
value="0" onclick="getVote(this.value)">
<br>No:
<input type="radio" name="vote"
value="1" onclick="getVote(this.value)">
</form>
</div>
</body>
</html>

Example Explained - The HTML Form :

As you can see, the HTML page above contains a simple HTML form inside a "<div>" with two radio buttons.

The form works like this:

An event is triggered when the user selects the "yes" or "no" option

When the event is triggered, a function called getVote() is executed.

Around the form is a
called "poll". When the data is returned from the getVote() function, the return data will replace the form.

Text File :

The text file (poll_result.txt) is where we store the data from the poll. It is stored like this : 0||0

The first number represents the "Yes" votes, the second number represents the "No" votes.

Note: Remember to allow your web server to edit the text file. Do NOT give everyone access, just the web server (PHP).

JavaScript :

The JavaScript code is stored in "poll.js" and linked to in the HTML document:

CODE/PROGRAM/EXAMPLE

var xmlHttp
function getVote(int)
{
xmlHttp=GetXmlHttpObject()
if (xmlHttp==null)
{
alert ("Browser does not support HTTP Request")
return
}
var url="poll_vote.php"
url=url+"?vote="+int
url=url+"&sid="+Math.random()
xmlHttp.onreadystatechange=stateChanged
xmlHttp.open("GET",url,true)
xmlHttp.send(null)
}
function stateChanged()
{
if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
{
document.getElementById("poll").
innerHTML=xmlHttp.responseText;
}
}
function GetXmlHttpObject()
{
var objXMLHttp=null
if (window.XMLHttpRequest)
{
objXMLHttp=new XMLHttpRequest()
}
else if (window.ActiveXObject)
{
objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP")
}
return objXMLHttp
}

getVote() Function :

This function executes when "yes" or "no" is selected in the HTML form.

Defines the url (filename) to send to the server

Adds a parameter (vote) to the url with the content of the input field

Adds a random number to prevent the server from using a cached file

Calls on the GetXmlHttpObject function to create an XMLHTTP object, and tells the object to execute a function called stateChanged when a change is triggered

Opens the XMLHTTP object with the given url.

Sends an HTTP request to the server

PHP Page :

The server page called by the JavaScript code is a simple PHP file called "poll_vote.php".

CODE/PROGRAM/EXAMPLE

<?php
$vote = $_REQUEST["vote"];
//get content of textfile
$filename = "poll_result.txt";
$content = file($filename);
//put content in array
$array = explode("||", $content[0]);
$yes = $array[0];
$no = $array[1];
if ($vote == 0)
{
$yes = $yes + 1;
}
if ($vote == 1)
{
$no = $no + 1;
}
//insert votes to txt file
$insertvote = $yes."||".$no;
$fp = fopen($filename,"w");
fputs($fp,$insertvote);
fclose($fp);
?>
<h2>Result:</h2>
<table>
<tr>
<td>Yes:</td>
<td>
<img src="poll.gif"
width="<?php echo(100*round($yes/($no+$yes),2)); ?>"
height="20">
<?php echo(100*round($yes/($no+$yes),2)); ?>%
</td>
</tr>
<tr>
<td>No:</td>
<td>
<img src="poll.gif"
width="<?php echo(100*round($no/($no+$yes),2)); ?>"
height="20">
<?php echo(100*round($no/($no+$yes),2)); ?>%
</td>
</tr>
</table>

The selected value is sent from the JavaScript and the following happens:

Get the content of the "poll_result.txt" file

Put the content of the file in variables and add one to the selected variable

Write the result to the "poll_result.txt" file

Output a graphical representation of the poll result

#AJAX_Poll_in_php #PHP_and_AJAX_Poll #getVote()_Function

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