（PHP）存储点击的IP地址

Question

After almost 3 days of troubleshooting I gotta ask for advice.

A have a small imageboard with 4 images and 4 'like' buttons. Earlier I made it so the number of clicks with each button stores in a .txt file. Now I basically need to make it so a person can press a certain button only once.

This is ip.txt. The number to the left is button ID, to the right is IP of the person that clicked that button.

click-001||127.0.0.1
click-002||

This is very simple. I need to make sure it stores ip when I click on my PC, then stores another IP when I click on my pad - and stops whatever I do next. Now for the last few days it's been doing anything except that!

My current code with isset. That sees the first IP but doesn't add the second:

$file2 = 'ip.txt'; // path to text file that stores counts
$fh2 = fopen($file2, 'r+');
$ip_addr = $_SERVER['REMOTE_ADDR'];
$lines2 = '';
while(!feof($fh2)) {
    $line2 = trim(fgets($fh2));
    if ($line2) {
        $line2 = explode('||', $line2);
        if(isset($line2[0], $line2[1])) {
            $item2 = trim($line2[0]);
            if(!empty($item2)) {
                if($item2 == $id) { 
                    if(empty($line2[1])) {
                        $lines2 .= "$item2||$ip_addr
";
                        file_put_contents($file2, $lines2);
                    } else {
                        // this is where it always fails
                        if (!isset($ip_addr)) {                             $ip_all = $line2[1] . " " . $ip_addr;
                            $lines2 .= "$item2||$ip_all
";
                            file_put_contents($file2, $lines2); 
                        } else {
                            echo "lul"; 
                        }
                    } 
                } 
            }
        }
    }
}
fclose($fh2);

I also tried this with in_array function:

$ip_all = array($line2[1]); 
    if (!in_array($ip_addr, $ip_all)) {
        array_push($ip_all, ',' , $ip_addr);            
        $ip_fin = implode($ip_all);
        $lines2 .= "$item2||$ip_fin
";
        file_put_contents($file2, $lines2); 

^ This one also sees the first IP and adds the second, but then fails to find whether the IP is already there and just keeps adding copies when I click.

This is brutal. What am I doing wrong and is there an easier way?

Answer 1

Use MySQL database to accomplish this.
Using a text file is super inefficient and can cause conflicts when multiple users liked at the same time!

Insert the IP to database everytime a user clicked the 'Like' button and then use a select query to determine if this IP has liked the picture before.

I do not recommend using just IP tho as some ISP gives dynamic IP that changes the IP (Public IP) address every few seconds.
Use cookies to store a unique cookie for a user (if they are not logged in) or just ask the user to login first before voting!

Information about MySQL Insert and Select are everywhere on Google.
Here's one : https://www.w3schools.com/sql/