Passing Existing Website Information to PHP/MySQL Database WITHOUT FORM

Question

There is a similar question, it is 7 years old and not very helpful for my situation. Didn't want to frustrate anyone into thinking I didn't search. Everything else I've searched for has dealt with forms, which isn't what I need. I have the C# background and am not very familiar with PHP, so bear with me.

I have a forum hosted by another service, this service has their own database and such for storing users. This service doesn't support a function I'm trying to incorporate so I'm attempting to host my own database and do it myself.

Here's the current situation:

• Forum database holds user information, such as UserIDs, to which are unique to the users. I want my database to correspond.
• I need to send the logged in user's ID to my database, without putting in a form and asking them to give me their user ID.
• I have access to the variable that holds their ID, and just need to know how to pass it over. I can't change the forum to a.PHP and just send it from the main page.

My biggest problem:

• Most of the information I've found is outdated/depreciated.

• I know JS/AJAX can be used for this, but I haven't seen any examples other than for form and I have no idea how to change it to just sending the already populated variable to my PHP file that will upload it to my database.

  var id= '<!--|id|-->';
  window.location.href = "myphpfile.php?id=" + id; 
  

This is as close as I've gotten, it does what I want, but it takes my users away from the forum in order to submit this. Is there a way of passing it to the file without needing to redirect the page? Any help is appreciated, especially if you can explain to me how it works/why it works.

Answer 1

Do you have jQuery? Since you have your PHP file that writes to your DB as a separate file, you can use $.post from that page to call that file.

 $.post('path/to/phpfile.php', {loginId: <put the login id here>})
    .done( function(data) {
            <if you wanna do something once the operation is done>
    });

Then on the PHP file, you can grab it via $_POST['loginId']. Then do your processing there, and echo something back if you want.

---

Or if you want the vanilla js method you can refer to this question answered here: Send POST data using XMLHttpRequest

Answer 2

Well, If I understood you you could make it like this:

Lets say the User_ID is in $_SESSION['id'] you could just:

$.ajax({

    url : 'yourphpscript.php',
    type : 'POST', //If it wants a POST, you may change it to GET
    data : {
        'id' : <?php echo $_SESSION['id']; ?> //or where ever your variable is
    },
    success : function(data) {              
        //Do something on success
    },
    error : function(request,error)
    {
        //Do something on error
    }
});

Just place this with an onload, you should be fine :)

EDIT: But be aware that Users could start sending fake data, that may be or not be a problem