如何将规范标签添加到OpenCart页面？

I’ve created a new OpenCart 1.5.6 store – http://www.example.eu - however, a lot of its pages are identical (in terms of text context) to pages in an old store which is still running – http://www.example.co.uk

With both sites indexed, I’d like to reference all identical pages at the old site by including canonical tags in the new site:

e.g. The “About Us” page at http://www.example.eu/about-us should ideally have something like that in its head section:

<link rel="canonical" href="http://www.example.co.uk/delivery"/>

e.g. The “Delivery” page at http://www.example.eu/delivery should ideally have something like that in its head section:

<link rel="canonical" href="http://www.example.co.uk/delivery"/>

I’m aware how that can be achieved in theory, but cannot apply it in practice. Additionally, while I’m mostly concerned about all the Information-type pages, ideally I’d love to be able to specify the exact pages that will have the canonical tag, something like:

If (this page is About-Us OR Delivery OR … OR … OR … OR …)
{
Include Canonical Tag of the type <link rel="canonical" href="http://www.example.co.uk/xxxxxxxx"/> , 
where xxxxxxx changes accordingly, depending on the page.
}
Else
{
Don’t include Canonical Tag
}

The best way to achieve this is to modify your Document class, set your canonical in your controller, then render it in the header controller.

Edit system/library/document.php

add:

private $canonical; to your class variables up top.

Then add the following methods:

public function setCanonical($url) {
    $this->canonical = $url;    
}

public function getCanonical() {
    return $this->canonical;
}

In your header controller add:

$this->data['canonical'] = $this->document->getCanonical();

Then you can set your canonical dynamically in the header controller:

if (isset($this->request->get['_route_'])):
    $canonical_route = $this->request->get['_route_'];
else:
    $canonical_route = '';
endif;

$this->document->setCanonical($this->data['base'] . $canonical_route);

Or you can set it manually in your controllers using the setCanonical method.