通过url将product_id值传递给额外添加的页面

I am using OpenCart. I want to give a link from product_form.tpl to another page. I mean I have added a tab called 'Allocation' in which I have given a button 'Add Allocation' which should redirect an external page. I'd like also to provide the product_id within this link but it's not working properly...

Here is my code (product_form.tpl)

<div id="tab-allocate">
        <table class="list"><tr><td align="center"><a href="allocation.php?product_id=&product_id" target="_blank" class="copybutton" style="width:120px;">ADD ALLOCATION</a></td></tr></table>
        </div>

But allocation.php?product_id=&product_id is not working, it goes to allocate.php page but doesn't carry the product_id. What am I doing wrong?

I think, it's something wrong in your passing parameter, please try like that

<a href="allocation.php?product_id=product_id" target="_blank" class="copybutton" style="width:120px;">

Your previous style work to pass two parameter. eg <a href="allocation.php?product_id=product_id&second_id=Second_id" target="_blank" class="copybutton" style="width:120px;">

Hope this help

Ps. You can also use like that $this->request->post['product_id'] OR $this->request->get['product_id']

What a messy HTML...

Change that link to this one:

<a href="allocation.php?product_id=<?php echo $result['product_id']; ?>" target="_blank" class="copybutton" style="width:120px;">ADD ALLOCATION</a>

This should work. And put the CSS styles into the CSS files (catalog/view/themes/<YOUR_THEME>/css/stylesheet.css).