PHP - Show Content In The Future?

Hi,

I have made a database linked with php that I use a html form for.

The HTML form requests a particular date to retrieve, and the php form it is linked to then retrieves data from the MySQL database from that date.

My question is: I want there to be a restriction so that the retrieval can only be for dates before the present date (and certainly not any date in the future).

e.g. if it is 6th July 2020, then the database can only retrieve from the 5th July 2020 and before. (7th July 2020 onwards also is not allowed.)

Is there a way I can do it? Anyone who can guide me to a particular code function or something of that sort - I would be deeply grateful as my searches have not come up fruitful.

I was trying to prevent bottlenecks when sending emails, and the below post was the solution.

Similar predicament now, but I also need to generate some images first so they may be attached to the emails and the images are generated by a fairly slow command line program that emulates a browser.  Multiple emails might or might need the same image so I plan on creating all the images before queuing the emails.

I believe the futureTick approach executes each tick in series as blocking, but doesn't attempt to execute all of them at once so it doesn't impact the rest of the application.  Promises, however, appear to be more about a structured process for managing callback functions.  As such, the futureTick approach would likely be best for tasks requiring much PHP processing, and promises are more suitable for tasks which PHP is just waiting for a response from some other service.  True?

Would one ever want to attempt to use both approaches?  Seems like it might make sense if the code within a promise was PHP intensive to break it down into multiple futureTick tasks, but not not feed promises into the futureTick as promises are "kind of" non-blocking, true?

To execute the CLI image program, considering https://github.com/clue/reactphp-shell.  Or do you think plan old exec() would be applicable?

For using promises, would it just look something like the following?

$deferred = new React\Promise\Deferred();

$deferred->promise()
->then(function ($rs) {
    // create the first image
})->then(function ($rs) {
    // create the second image
})->then(function ($rs) {
    // create the last image
})->then(function ($rs) {
    // send the first email
})->then(function ($rs) {
    // send the second email
})->then(function ($rs) {
    // send the last email
});

$deferred->resolve($nothing?); 

Or maybe something like the following?  I would be amazed if it works as is, but hopefully is on the right track.

$deferred = new React\Promise\Deferred();
$deferred->promise()
->then(function ($rs) {
    // Create images
    // See https://github.com/clue/reactphp-shell
    $launcher = new ProcessLauncher($loop);
    $shell = $launcher->createDeferredShell('bash');

    $shell
    ->execute('create the first image')
    ->execute('create the second image')
    ->execute('create the lst image')
    
    ->then(function ($rs) use($loop) {
        // Send emails
        // Just showing this way but will actually use kicken's EmailQueue solution
        $loop->futureTick(function () {
            // send the first email
        });
        $loop->futureTick(function () {
            // send the second email
        });
        $loop->futureTick(function () {
            // send the last email
        });
    });
});

$deferred->resolve($someQueueOfImages?); 

I want to show a cookie of a referral's username on a sign up page. The link is like this, www.mysite.com/signup?ref=johnsmith.

The cookie doesn't show if I go to that url page. But it does show up once I reload the page.  So I'm wondering if it's possible to show the cookie the first time around, instead of reloading the page?

Here is my code.

// This is in the header
$url_ref_name = (!empty($_GET['ref']) ? $_GET['ref'] : null);

if(!empty($url_ref_name)) {

  $number_of_days = 365;
  $date_of_expiry = time() + 60 * 60 * 24 * $number_of_days;
  setcookie( "ref", $url_ref_name, $date_of_expiry,"/");

} else if(empty($url_ref_name)) {
  if(isset($_COOKIE['ref'])) {
    $user_cookie = $_COOKIE['ref'];
  }
} else {}

// This is for the sign up form
if(isset($_COOKIE['ref'])) {
  $user_cookie = $_COOKIE['ref'];
  ?>
  <fieldset>
    <label>Referred By</label>
    <div id="ref-one"><span><?php if(!empty($user_cookie)){echo $user_cookie;} ?></span></div>
    <input type="hidden" name="ref" value="<?php if(!empty($user_cookie)){echo $user_cookie;} ?>" maxlength="20" placeholder="Referrer's username" readonly onfocus="this.removeAttribute('readonly');" />
  </fieldset>
  <?php
}