Get value of input field using php into variable

Question

I have already refered to this question and the accepted answer did not work for me: How to get input field value using PHP

This is my code result.php file:

...
<th> 
    <form name="form" action='checkout.php' method='POST'>
         <input class='mx-2' type='number' id='price' name='price' placeholder='Donation Amount'">
    </form>
</th>  
<script
    src='https://checkout.stripe.com/checkout.js' class='stripe-button'
    data-key='key'
    data-amount=get value of input field with id price here
    data-name='Name'
    data-description='Description'
    data-currency='usd'
    data-locale='auto'>
</script>     
...

I have also tried fetching the value of the input like this and then using that variable:

<?php $price = isset($POST['price']) ? $POST['price'] : 0; ?>

Another method I tried:

<?php
$htmlEle = "<span id='SpanID'>Span Sports</span>";
$domdoc = new DOMDocument();
$domdoc->loadHTML($htmlEle);

$spanValue = $domdoc->getElementById('SpanID')->nodeValue;

I found the above snippet on https://phpcoder.tech/how-to-get-html-tag-value-in-php/ and modified it as per my need but did not work.

How can I do this? My app is pay what you want so I want the price to be filled in by the user on the client side.

I am open to different approaches and solutions to the one I asked for.

Answer 1

If you don't want to wait for the client to submit the form, you will need some javascript as PHP is a server-rendering language.

Basically you would need to set-up a listener on the input and after the client types the data in a format you want and you validate it, you can pass that to stripe script.

Answer 2

You have used the wrong POST syntax, the correct is: $_POST, while you are trying get: $POST.

The docs: https://www.php.net/manual/en/reserved.variables.post.php

--In JavaScript part--

If you want to handle PHP the price before call Stripe, you should use other configuration, because this one will not work anyway.

You can:

• call Stripe on like ajax or other request that in background post the forst
• call Stripe on other page
• don't do form, just plain text field (if you don't need PHP, handle price before Stripe request)

It depends what you want to do.

Answer 3

<th> 
    <form name="form" action='checkout.php' method='POST'>
         <input class='mx-2' type='number' id='price' name='price' placeholder='Donation Amount'">
         <input type="submit"> 
    </form>
</th> 

submit button in missing here, so add a submit button.

And update your PHP code

<?php $price = isset($_POST['price']) ? $_POST['price'] : 0; ?>

$_POST - is PHP Superglobals for getting form's post values. $POST (which you are using) is a normal PHP variable.

Please update your code like this.It will works.

Answer 4

I used a different method to solve the problem. I put the text box on a separate page and the pay button on the checkout page, so I am passing the price from the previous page to the checkout page now and accessing it using query parameters

Answer 5

<form name="form" action='checkout.php' method='POST'>
         <input class='mx-2' type='number' id='price' name='price' placeholder='Donation Amount'">

<button name="submit" type="submit" >submit button</button>
   </form>

///in checkout.php code

if(isset($_POST['submit']){
    $price = $_POST['price'];
    echo $price;
}

///I hope this would work