Voting Poll

This snippet shows you how to create a simple yes/no voting poll on your site.

STRUCTURE

A form which accepts a yes or no input. Then through the use of some <div> tags styled with CSS we can graphically display the results.

CODE

<?php
require_once('mimesis/Mimesis.php');

$cwd = realpath(dirname(__FILE__));
$tableName = 'votes';
$permissions = 0644;
$rowLabel = str_replace('.', '_', $_SERVER['REMOTE_ADDR']);

$mimesis = new Mimesis($cwd, $tableName, 'ts_' . $tableName, $permissions);

if(isset($_POST['yes']) || isset($_POST['no'])){
	if($mimesis->lock(1)){
		if(false === @$mimesis->getRow($rowLabel, $rowLabel)){
			if(isset($_POST['yes'])){
				if(!$mimesis->insertRow(array($rowLabel => array('vote' => true))))
					echo 'Unable to insert row into table.';
			}else{
				if(!$mimesis->insertRow(array($rowLabel => array('vote' => false))))
					echo 'Unable to insert row into table.';
			}
		}else{
			echo 'Your IP address has already entered a vote.';
		}
		if(!$mimesis->release())
			echo 'Unable to release lock on table.';
		}
	}else{
		echo 'Unable to lock table.';
	}
}

if($mimesis->tableExists()){
	$poll = $mimesis->query();
	$votes = array(
		'yes'	=> 0,
		'no'	=> 0
	);
	foreach($poll as $value){
		if($value['vote'])
			$votes['yes']++;
		else
			$votes['no']++;
	}
	echo '<div style="width: 45%; border: solid 1px black;">';
	echo '<div style="width: ' . ($votes['yes'] / count($poll) * 100) . '%; background-color: #00ff00;">';
	echo $votes['yes'];
	echo '</div>';
	echo '<div style="width: ' . ($votes['no'] / count($poll) * 100) . '%; background-color: #ff0000;">';
	echo $votes['no'];
	echo '</div>';
	echo '</div>';
}else{
	echo 'No votes cast.';
}

echo '<form method="POST" action="' . basename(__FILE__) . '">';
echo '<p><input type="radio" name="yes" CHECKED> Yes</p>';
echo '<p><input type="radio" name="no"> No</p>';
echo '<input type="submit">';
echo '</form>';
?>

KEY CONCEPTS

Some of the important things to keep in mind when viewing this code are the following:

We use the IP address as provided by the $_SERVER['REMOTE_ADDR'] to create the row labels for our entries
So long as $_POST['yes'] is set it is automatically assumed to be a yes vote, if it is not set then vote will always be a no
We test to see if an IP address already exists in our table by checking for its label (this means this person, or at least their ip address, has already cast a vote)
To determine the percentages of votes we count the number of yes votes and number of no votes and divided them by the total votes
Permission 0644 is used in this example because on the 110mb.com server 0644 corresponds to the most accessible php script permissions
The lock performed here is a polling lock, which means it won't stop trying until it acquires a lock on the table OR the script times out
We display errors in every possible location where one might occur