WordPress Dropin: Getting popular Tags by Category

chrico_get_popular_tags_by_category.php

<?php
/**
 * Fetching popular Tags from a category
 *
 * @param   Array $args
 * @return  String $output
 */
function chrico_get_popular_tags_by_category( Array $args = array() ){


	// our default args to generate the output
	$default_args   = array(
		'max_items'     => 5,
		'link'          => '<a href="%1$s">%2$s (%3$s)</a>',
		'link_separator'=> ' | ',
		'link_before'   => '',
		'link_after'    => '',
		'before'        => __( '<h3 class="pota">Popular tags in this category:</h3><p> ', 'chrico' ),
		'after'         => '</p>',
	);

	// getting the current category as default, if exists
	if( is_category() ) {
		$query_var  = get_query_var( 'cat' );
		$category   = get_category( $query_var );

		if( !is_wp_error( $category ) ) {
			$default_args[ 'category_id' ] = $category->cat_ID;
		}
	}

	$args = wp_parse_args( $args, $default_args );
	/**
	 * arg filter to manipulate the $args
	 * @param	Array $args
	 * @param	Array $default_args
	 */
	$args = apply_filters( 'chrico_get_popular_tags_by_category_args', $args, $default_args );

	if( !isset( $args[ 'category_id' ] ) || empty( $args[ 'category_id' ] ) ) {
		return '';
	}

	// fetching all posts in this category
	$post_args = array(
		'category'      => $args[ 'category_id' ],
		'fields'        => 'ids',
		'numberposts'   => -1
	);
	$posts  = get_posts( $post_args );

	if( empty( $posts ) ) {
		return '';
	}

	// searching for tags and sorting them.
	$tag_order      = array();
	$tags           = array();
	$post_tag_args  = array(
		'orderby'   => 'count',
		'order'     => 'DESC'
	);
	foreach( $posts as $post_id ) {

		// getting all post_tags
		$post_tags = wp_get_post_tags( $post_id, $post_tag_args );

		// looping through them and adding the count
		foreach( $post_tags as $tag ) {

			if( !array_key_exists( $tag->slug, $tags ) ) {
				$tag_order[ $tag->slug ]= 0;
				$tags[ $tag->slug ]	= $tag;
			}
			$tag_order[ $tag->slug ] += 1;
		}
	}

	// no tags to order? break.
	if( count( $tag_order ) < 1 ) {
		return '';
	}

	// sorting the tags from high to low
	arsort ( $tag_order );

	// we don't need all items, do we?
	if( $args[ 'max_items' ]  !== -1 ) {

		$tag_order = array_slice(
			$tag_order,
			0,
			$args[ 'max_items' ]
		);

	}

	// generating the output~
	$output     = '';
	$counter    = 1;
	$count_tags = count( $tag_order );

	foreach( $tag_order as $tag_slug => $count ) {

		$tag		= $tags[ $tag_slug ];
		$term_link	= get_term_link( $tag->slug, 'post_tag' );

		// building the link
		$link = sprintf(
			$args[ 'link' ],
			$term_link,
			$tag->name,
			$count
		);

		$output .= $args[ 'link_before' ];
		$output .= $link;

		if( $counter < $count_tags ) {
			$output .= $args[ 'link_separator' ];
		}

		$output .= $args[ 'link_after' ];

		$counter++;
	}

	// building the context-array for return-filter
	$context = array(
		'tag_order' 	=> $tag_order,
		'tags'		=> $tags,
		'posts'		=> $posts,
		'post_args'	=> $post_args,
		'post_tag_args' => $post_tag_args,
		'args'		=> $args,
		'default_args'	=> $default_args
	);

	// the html-output
	$html = $args[ 'before' ] . $output . $args[ 'after' ];


	/**
	 * return filter to manipulate the output
	 * @param	String $html
	 * @param	Array $context array(
				'tag_order'	=> Array,
				'tags' 		=> Array,
				'post_tag_args'	=> Array,
				'posts' 	=> Array,
				'post_args' 	=> Array,
				'args'		=> Array,
				'default_args	=> Array
			)
	 */
	return apply_filters( 'chrico_get_popular_tags_by_category', $html, $context );
}

examples.chrico_get_popular_tags_by_category.php

<?php
/**
 * get popular tags when is_category()
 */
echo chrico_get_popular_tags_by_category();

/***************************************/
/**
 * get tags by category 5
 */
$args = array(
 	'category_id' => 5
);
echo chrico_get_popular_tags_by_category( $args );
 
/***************************************/
/**
 * get more tags by category
 */
$args = array(
 	'max_items' => 10
);
echo chrico_get_popular_tags_by_category( $args );
 
/***************************************/
/**
 * get ALL tags by category
 */
$args = array(
	'max_items' => -1
);
echo chrico_get_popular_tags_by_category( $args );
 
/***************************************/
/**
 * format the output as an ulli with a h4 headline before :)
 */
$args = array(
	'before'	=> '<h4>' . __( 'My custom before text', 'chrico') . '</h4><ul>',
	'after'		=> '</ul>',
	'before_link'	=> '<li>',
	'after_link'	=> '<li>'
	'link'		=> '<a href="%1$s"><span class="title">%2$s</span> <span class="count">%3$s</span></a>',
	'link_separator'=> ' - '
);
echo chrico_get_popular_tags_by_category( $args );
 
/***************************************/
/**
 * same as above, but using the filter~
 */
add_filter( 'chrico_get_popular_tags_by_category_args', 'demo_filter_chrico_get_popular_tags_by_category_args' );
 
/**
 * arg-filter-callback to manipulate the $args
 * @param	Array $args
 * @return	Array $args
 */
function demo_filter_chrico_get_popular_tags_by_category_args( Array $args ) {

	$args[ 'before' ]		= '<h4>' . __( 'My custom before text', 'chrico') . '</h4><ul>';
	$args[ 'after' ]		= '</ul>';
	$args[ 'before_link' ]		= '<li>';
	$args[ 'after_link' ]		= '<li>';
	$args[ 'link' ]			= '<a href="%1$s"><span class="title">%2$s</span> <span class="count">%3$s</span></a>';
	$args[ 'link_separator' ]	= ' - ';

	return $args;
}
 
/***************************************/
/**
 * filter the output
 */
add_filter( 'chrico_get_popular_tags_by_category_args', 'demo_filter_chrico_get_popular_tags_by_category' );
 
/**
 * return-filter-callback to manipulate the output by adding a <section> around
 * @param	String $html
 */
function demo_filter_chrico_get_popular_tags_by_category( $html ) {
	$html = '<section>' . $html . '</section>';
	return $html;
}
 
 /***************************************/
 /* to be continued... */