如何在 php 表单重定向后增加一个数字？

Question

I'm building a simple count display for a website and I need it to only increment after the form successfully submits. The form is a simple HTML form that uses PHP mail() function to send the information and redirects back to the page.

    let clicks = Number(document.getElementById("clicks").innerHTML);
    function stateInc() {
        clicks += 1;
        document.getElementById("clicks").innerHTML = clicks;
    }

I thought maybe I would use the onClick="function()" tag inside the button to call a function to increment the number on page which is stored in a tag with the appropriate id reference.

    <p class="for-text">State Hats Ordered:  <a id="clicks">0</a></p>

    <p><button class="for-text" id="clicker" formaction="mailform.php" onclick="stateInc()" style="color: darkred; padding: 8px 8px; margin: 4px;">Submit Order</button></p>

I was hoping to do the increment before leaving the page or even in the php form, but I'm not sure how I would do that and so far what I've attempted hasn't worked thus far.

I also thought I would try doing a redirect within the javascript function above to go to the form mailer script, but for obvious reasons that wouldn't work due to not having the form information by the time the redirect happens.

Thanks in advance!

Answer 1

There two ways:

1. Storing on client side

Advantage: It's cheap and easy

Disadvantage: counts are user specific and not global/total. Therefore noone can tell how often a page has been submitted.

let clicks = localStorage.getItem("clicks") || 0; // get value
clicks++;
document.querySelector("#clicks").innerText = "You've visited this page " + clicks + " time(s)"; // display on webpage
localStorage.setItem("clicks", clicks); // save value to client

2. Storing on server side (Highly recommended)

Advantage: Total count

Disadvantage: Takes a lil' bit more effort

Since you are using php I assume you'd rather use mysql. You have to create a database and a new table in it. From this point you could track the visit or just the counter. For instance, you could create the following table: visits(id, ip, time, url) Then you establish a mysql connection and run this sql command INSERT INTO visits (ip, time, url) VALUES(?,?,?) Keep in mind that you don't want any security issues especially when it comes to sql injections. if you've never heard of it, you should definitely read about it.

To display the amount of visits run this sql command after the previous one: SELECT COUNT(id) FROM visits

To store the visit:

$db = new mysqli('localhost', 'my_user', 'my_password', 'my_db');

$query = $db->prepare("INSERT INTO visits (ip, time, url) VALUES(?,?,?)");
$query->bind_param("sss", $_SERVER["REMOTE_HOST"], date("Y-m-d H:i:s"), $_SERVER["REQUEST_URI"]);
$query->execute();
$query->close();
$db->close();

To display the visit counter:

$db = new mysqli('localhost', 'my_user', 'my_password', 'my_db');

$query = $db->prepare("SELECT COUNT(id) FROM visits WHERE url = ?");
$query->bind_param("s", $_SERVER["REQUEST_URI"]);
$query->bind_result($clicks);
$query->execute();
$query->fetch();
echo "This page was" . $clicks . " time(s) visited";
$query->close();
$db->close();

Notice: Make sure you implement error checking before running this in production

In the end it might be easier to just leave it out or save the page count to a file if you not sure how to use mysql.

Answer 2

try to use PHP Session.

A session is started with the session_start() function.

Session variables are set with the PHP global variable: $_SESSION.

Answer 3

If you just need to increment your counter without anything else after that, you can store the value of the current counter in a .txt file on your server and use it each time to check the current value and then, increment 1 after your form is sended.

BUT as Kevin says, the best way is to store it with php in a small database.

Answer 4

If your not going to use a database then the best way to do this in a file is to simply append a new line.

When trying to update a value stored in the file, you have to read that value, change it in PHP, then save it. If it's not done with an exclusive lock on the file you could have concurrency and race issues. Basically 2 processes can read it, one increments it, then the other increments the old value so you miss a increment or worse.

So you can just append a new row and then there is no read involved in updating the count.

 file_put_contents($filename, "1\n",  FILE_APPEND);

So then how do we count the lines in the file, the number of lines equal the number of increments.

$Obj = new SplFileObject($filename, 'r');
$Obj->seek(PHP_INT_MAX); //seek to the max PHP int, or the end of the file
$line = $Obj->key();

Answer 5

You should manage the counter in PHP and show the updated value in the form page. You could store the value in a database.