Adding a Link to the Information sidebox

This page continues the FAQ on customizing the Information Sidebox. It is such a common question is has been pulled out to its own page.

There are three techniques that can be used to add links to the “Information”, More Information and EZ-Pages (aka “Important Links”) sideboxes.

1. Using a Template Override
2. Using a Sidebox Module Override
3. Using an Observer. Available for Zen Cart versions 2.0.1 and later, but easily backported.

Using a Template Override

To add a link to the Information Sidebox, we create the override file includes/templates/YOURTEMPLATE/sideboxes/tpl_information.php.

Edit this file.

Add your link before the list’s ending ul tag:

$content  .= '</ul>' . "\n";

For example, linking to an external page:

$content .= '<li><a href="https://www.zen-cart.com/" target="_blank" rel="noreferrer noopener">The Greatest Shopping Cart Ever!</a></li>' . "\n" ;

Note: In subsequent examples, the appended linefeed . "\n" is dropped for clarity.

If the link if to an internal page, use the zen_href_link function. For example, if you have a page called “News” (and have defined FILENAME_NEWS and BOX_INFORMATION_NEWS), a link to this page may be added to the Information Sidebox with

$content .= '<li><a href="' . zen_href_link(FILENAME_NEWS) . '">' . BOX_INFORMATION_NEWS . '</a></li>';

If the link is to an internal EZ-Page, use

$content .= '<li><a href="' . zen_href_link(FILENAME_EZPAGES,'id=9') . '">' . "My new page" . '</a></li>';

or if you don’t want to modify code, you can just use the EZ-Pages sidebox, which displays EZ-Pages with sidebox display on and a positive sort order.

Using a Sidebox Module Override

Purists would argue that it’s not a good practice to update the template to add links, and that instead, the relevant module file should be updated. The approach used above is more beginner friendly and lends itself to copy-and-paste ready examples for all three sideboxes, which is why it was chosen.

You could accomplish what’s done in the first example - add a link to zen-cart.com to the Information sidebox - by creating the override file includes/modules/sideboxes/YOURTEMPLATE/information.php, and then modifying it just before the require statements to add

$information[] = '<a href="https://www.zen-cart.com/" target="_blank" rel="noreferrer noopener">The Greatest Shopping Cart Ever!</a>'; 

The same process could be used to add a link to the More Information sidebox, using the $more_information array in place of $information.

However, adding a link to the EZ-Pages sidebox using this technique would be more involved, since the entries in $var_linksList are arrays, not simple strings.

Using an Observer

Starting with Zen Cart 2.0.1, these sideboxes include a notification to enable the insertion of additional links in the sideboxes’ displays. Each notification enables a watching observer to insert additional links into those sideboxes’ display, making the template-override techniques above obsolete.

• “Information” (/includes/modules/sideboxes/information.php)
• “More Information” (/includes/modules/sideboxes/more_information.php)
• “Important Links” (/includes/modules/sideboxes/ezpages.php)

Each sidebox’s notification provides a numerically-indexed array of links (as HTML anchor tags) to be included in the sidebox’s display.

Information Sidebox

The “Information” sidebox now includes the following notification:

$zco_notifier->notify('NOTIFY_INFORMATION_SIDEBOX_ADDITIONS', [], $information);

An observer can attach to that notification to insert additional links seamlessly into that sidebox. Note that the Bootstrap template provides a variable ($information_classes) with additional classes to be included in that sidebox link. A modification that requires support for that template as well as the built-in responsive_classic template should, if that variable isset, include that variable’s value in a class= attribute for each inserted link. You’d have code similar to

$link_class = (isset($information_classes)) ? ('class="' . $information_classes . '"') : '';

More Information Sidebox

The “More Information” sidebox now includes the following notification:

$zco_notifier->notify('NOTIFY_MORE_INFORMATION_SIDEBOX_ADDITIONS', [], $more_information);

An observer can attach to that notification to insert additional links seamlessly into that sidebox. Note that the Bootstrap template provides a variable ($more_information_classes) with additional classes to be included in that sidebox link. A modification that requires support for that template as well as the built-in responsive_classic template should, if that variable isset, include that variable’s value in a class= attribute for each inserted link. You’d have code similar to

$link_class = (isset($more_information_classes)) ? ('class="' . $more_information_classes . '"') : '';

Important Links Sidebox

The “Important Links” sidebox now includes the following notification:

$zco_notifier->notify('NOTIFY_EZPAGES_SIDEBOX_ADDITIONS', [], $var_linksList);

An observer can attach to that notification to insert additional links seamlessly into that sidebox.

Example Observer

Create the file includes/classes/observers/auto.information_sidebox.php as follows, using your own new links of course:

<?php
class zcObserverInformationSidebox extends base
{
    public function __construct()
    {
        global $current_page_base;
        $this->attach(
            $this,
            [
                'NOTIFY_INFORMATION_SIDEBOX_ADDITIONS',
            ]
        );
    }

    protected function update(&$class, $eventID, $not_used, &$information)
    {

       // Your links would be appended like this: 
       $information[] = '<a class="list-group-item list-group-item-action" href="' . zen_href_link('forms') . '">' . 'Forms'. '</a>'; 

    }
}

Common Observer Processing

For each of the above notifications, an observer processes the array of links provided in a similar manner. Let’s say that you want to insert the following link into one of the sideboxes:

$the_link = '<a href="' . zen_href_link(FILENAME_EZPAGES, 'id=25') . '</a>';

If you are also supporting the Bootstrap template, you’ll code that link as (based on the suggested variable name above)

$the_link = '<a ' . $link_class . ' href="' . zen_href_link(FILENAME_EZPAGES, 'id=25') . '</a>';

Now, to insert that link into the sidebox, you can use a PHP statement similar to the following

array_splice($links_array, $link_position, 0, $the_link);

where

• $links_array is the name of the variable in which you received the original array of sidebox links via the sidebox’s notification.
• $link_position is the zero-based position at which you want to insert that link. Use a value of 0 to insert the link as the first, 1 for the second and a large number, say 100 to insert that link at the end.
• $the_link is the anchor-link described above.

Backporting

To backport these notifiers to an earlier versions of Zen Cart, simply modify the relevant file in includes/modules/sideboxes (or the override folder if the file is overridden). For example, to add the Information sidebox notifier, update includes/modules/sideboxes/YOURTEMPLATE/information.php and after the last link is appended to the information array, add:

$zco_notifier->notify('NOTIFY_INFORMATION_SIDEBOX_ADDITIONS', [], $information);

• To backport for the EZ-Pages sidebox, modify includes/modules/sideboxes/ezpages.php (or the override), and add the notify call for NOTIFY_EZPAGES_SIDEBOX_ADDITIONS.
• To backport for the More Information sidebox, modify includes/modules/sideboxes/more_information.php (or the override), and add the notify call for NOTIFY_MORE_INFORMATION_SIDEBOX_ADDITIONS.

General Information

Specification of URLs

It’s a good practice not to hardcode non-relative URLs, in case your site moves or you want to reconstruct a test instance of it. So don’t do this:

$content .= '<li><a href="https://YOURSTORE.com/index.php?main_page=page&id=25">Important information</a></li>'; // NO 

Instead, use an URL relative to the top of your store (or better yet, use zen_href_link as in the examples above):

$content .= '<li><a href="index.php?main_page=page&id=25">Important information</a></li>'; // Better

You can read more about the importance of relative URLs to explore this topic in greater depth.

Mobile

You may need to make additional edits to control the link on mobile displays.

More Examples

See creating links to other pages.