title: Display a custom button with a dynamic Product ID using a shortcode in Woocommerce
body: <p>i using Wordpress button plugin called <a href="https://wordpress.org/plugins/maxbuttons/" rel="nofollow noreferrer">Max Button</a>s to generate button as  i want. But in that button creation into URL where need to point button have only URL where need to point button. This looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/3yCUx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3yCUx.png" alt="enter image description here"></a></p>
  
  <p>So as you can see, i use URL link to autoupdate coupon code to product and redirect to checkout.. But, that is for static product ID. So my question is how to generate that to each product , to autoget product ID at end of URL? MaxButton plugin generate shortcode where i inserting into place where i want.</p>
  
  <p>Current URL is:</p>
  
  <pre><code>https://testsite/checkout/?apply_coupon=5%off&amp;fill_cart=4004
  </code></pre>
  
  <p>How to get that <code>fill_cart=PRODUCT_ID</code> to be dynamic?</p>