Creating a basic rating system

[riderz]

Creating a basic rating system

In this tutorial I will show you how to create a basic and simple to use rating system. To make the script more simple and database independent we will use simple files to store rating information.

The basics

We divide the task into the following steps:

Display a HTML form where a visitor can select a rating.
Read the existing results
Check if the actual IP exists among the old results
Add valid rating to the result list
Display the actual rating

Displaying the HTML form

This is an easy part. As usually we create a normal HTML form which is displayed during the first call of the script. As the script itself contains the processing part as well we first check if we really need to display the form or process the submitted data. So the first part of the code looks like this:

echo $_SERVER['PHP_SELF']; ?>" method="post">

Your rating: 1 2 3 4 5

Read the existing results

As next step we need to process the user input. In this step we initialize some variables to store total ratings, total points, actual rating. This is quite simple:

$rate = isset ($_POST['rate']) ? $_POST['rate'] : 0;
$filename = "ratings";
$alreadyRated = false;
$totalRates = 0;
$totalPoints = 0;

$ip = getenv('REMOTE_ADDR');
?>

Afterwards we retrieve the actual user IP. Later we will check if this IP is already present in the result list. If we already have a result from the actual IP then we will ignore the new one. With this solution we can avoid to manipulate our ratings. So we need to open the result file and read it into an array using the file function. Next we iterate over this array and summarize the ratings until now. Of course we also check the IP:

// Read the result file
$oldResults = file('results/'.$filename.'.txt');

// Summarize total points and rates
foreach ($oldResults as $value) {
$oneRate = explode(':',$value);
// If our IP is in the list then set the falg
if ($ip == $oneRate[0]) $alreadyRated = true; 
$totalRates++;
$totalPoints += $oneRate[1];
}
?>

Now if the rating seems to be valid the we open the result file again and append a new result entry at the end of the file with the actual user IP. Besides this we update the total rating points we have collected in the previous step.

// If our rating is valid then append it to the result file
if ((!$alreadyRated) && ($rate > 0)){ 
$f = fopen('results/'.$filename.".txt","a+"); 
fwrite($f,$ip.':'.$rate."\n");
fclose($f);
$totalRates++;
$totalPoints+=$rate;
}
?>

As last step we only need to display the actual rating. We can do this with only displaying a the value or we can displaying some graphics like stars to make it a bit nicer.

echo "Actual rating from $totalRates rates is: "
.substr(($totalPoints/$totalRates),0,3)."
";

// Display the actual rating
for ($i=0;$i<round(($totalPoints/$totalRates),0);$i++){
echo "";
}
?>