Adding a Tag Parameter / Filter to My Shortcode

Question

I have this plugin that displays category featured image thumbnails for each post via shortcodes.. like so,

[categorythumbnaillist 3] (3 being the category of course)

I would like it to only show posts with the tag "news".. only if you set the tag value to "news" via the shortcode. So if you entered in...

[categorythumbnaillist 3 tag="news"]

Then it should only show posts with the news tag in it. If no tag is entered, it should then display the posts for the respective category like the plugin already does.

Here is the code I made for displaying the results.

$args=array(
      'showposts'=> 5,
      'category'=> $listCatId[1],
      'orderby'=> $categoryThumbnailList_OrderType,
      'order'=> $categoryThumbnailList_Order
       );

$myposts = get_posts( $args);
$output = '<div class="categoryThumbnailList">';
foreach($myposts as $post) :

I tried to read and understand Wordpress's shortcode API, but I just couldn't seem to wrap my head around it.

There are more functions from the plugin, So I have provided the full plugin code here: http://pastebin.com/QHrB8xUn

Any help to getting my plugin shortcode to filter results by the tag news (if entered) would truely be appreciated. :)

Answer 1

That plugin you have is not using the WordPress Shortcode API as it should be. There is not a single add_shortcode to be found. It has basically cooked up its own shortcode 'feature' by hooking a preg_replace_calback into the_content

define("categoryThumbnailList_REGEXP", "/\[categorythumbnaillist ([[:print:]]+)\]/");

define("categoryThumbnailList_TARGET", "###CATTHMBLST###");

function categoryThumbnailList_callback($listCatId) {

And:

function categoryThumbnailList($content) {
        return (preg_replace_callback(categoryThumbnailList_REGEXP, 'categoryThumbnailList_callback', $content));
}

And:

add_filter('the_content', 'categoryThumbnailList',1);

That is not really the way to do this. The normal shortcode functions aren't going to work correctly.

The callback function, categoryThumbnailList_callback, is only expecting an ID value, $listCatId, so what you are doing is going to take rewrite. You might be able to hack it by parsing that $listCatId value to extract your extra information-- try var_dump($listCatId); at the top of that function and see if you have anything usable. I'd have to install and run this to be able to write good code, but my recommendation is to rewrite the plugin to use the API correctly.

That plugin is listed as being for "WordPress 2.9 and up" so maybe it is just an old plugin, which would be another reason to rewrite.