I have a custom post type called shows and taxonomy called podcast. Using taxonomy-podcast.php, I having hard time finding a function that will generate next/previous Term URL Archive.
URL: url.com/podcast/example-term-2
Example Term 2
post 1,post 2,post 3
Desired output
< Previous Term(url.com/podcast/example-term-1) . . . . . | . . . . . Next Term(url.com/podcast/example-term-3)>
It is quite possible to achieve this. What we need to do is
Get all the terms sorted by slug (or any other field desired) associated with our taxonomy
Get the current term object
Determine where in the array our current term is
Get the two adjacent terms (if any)
Build the links to those term pages
I have written a function to take care of this. It ids always important to keep business logic out of templates. Templates should only know function names and not the entire function. This way, you keep your templates clean and maintainable
The function does require a minimum of PHP 5.4 and covers the basics, it is up to you to adjust it to your needs
function get_tax_navigation( $taxonomy = 'category' )
{
// Make sure we are on a taxonomy term/category/tag archive page, if not, bail
if ( 'category' === $taxonomy ) {
if ( !is_category() )
return false;
} elseif ( 'post_tag' === $taxonomy ) {
if ( !is_tag() )
return false;
} else {
if ( !is_tax( $taxonomy ) )
return false;
}
// Make sure the taxonomy is valid and sanitize the taxonomy
if ( 'category' !== $taxonomy
|| 'post_tag' !== $taxonomy
) {
$taxonomy = filter_var( $taxonomy, FILTER_SANITIZE_STRING );
if ( !$taxonomy )
return false;
if ( !taxonomy_exists( $taxonomy ) )
return false;
}
// Get the current term object
$current_term = get_term( $GLOBALS['wp_the_query']->get_queried_object() );
// Get all the terms ordered by slug
$terms = get_terms( $taxonomy, ['orderby' => 'slug'] );
// Make sure we have terms before we continue
if ( !$terms )
return false;
// Because empty terms stuffs around with array keys, lets reset them
$terms = array_values( $terms );
// Lets get all the term id's from the array of term objects
$term_ids = wp_list_pluck( $terms, 'term_id' );
/**
* We now need to locate the position of the current term amongs the $term_ids array. \
* This way, we can now know which terms are adjacent to the current one
*/
$current_term_position = array_search( $current_term->term_id, $term_ids );
// Set default variables to hold the next and previous terms
$previous_term = '';
$next_term = '';
// Get the previous term
if ( 0 !== $current_term_position )
$previous_term = $terms[$current_term_position - 1];
// Get the next term
if ( intval( count( $term_ids ) - 1 ) !== $current_term_position )
$next_term = $terms[$current_term_position + 1];
$link = [];
// Build the links
if ( $previous_term )
$link[] = 'Previous Term: <a href="' . esc_url( get_term_link( $previous_term ) ) . '">' . $previous_term->name . '</a>';
if ( $next_term )
$link[] = 'Next Term: <a href="' . esc_url( get_term_link( $next_term ) ) . '">' . $next_term->name . '</a>';
return implode( ' ...|... ', $link );
}
You can now just use the function where needed as follow:
echo get_tax_navigation( 'podcast' );
Just two questions: (1)When we are at the last term, can we still make the Next Term: (URL to the First term) and vise versa? Basically an infinite term loop. (2)For theming purposes, how can I use this function to output NEXT and PREVIOUS urls individually? (eg. get_tax_navigation( 'podcast', 'previous' ) and get_tax_navigation( 'podcast', 'next' )
When we are on the last of first term, all we need to do is either grab the first or last term depending on where we at. Obviously, when we are on the laste term, we will grab the first one, and vica-versa
We can introduce a $direction parameter which accepts three values, an empty string, previous or next
Here is an example of what you can do. You can adjust it from here to suite your needs
function get_tax_navigation( $taxonomy = 'category', $direction = '' )
{
// Make sure we are on a taxonomy term/category/tag archive page, if not, bail
if ( 'category' === $taxonomy ) {
if ( !is_category() )
return false;
} elseif ( 'post_tag' === $taxonomy ) {
if ( !is_tag() )
return false;
} else {
if ( !is_tax( $taxonomy ) )
return false;
}
// Make sure the taxonomy is valid and sanitize the taxonomy
if ( 'category' !== $taxonomy
|| 'post_tag' !== $taxonomy
) {
$taxonomy = filter_var( $taxonomy, FILTER_SANITIZE_STRING );
if ( !$taxonomy )
return false;
if ( !taxonomy_exists( $taxonomy ) )
return false;
}
// Get the current term object
$current_term = get_term( $GLOBALS['wp_the_query']->get_queried_object() );
// Get all the terms ordered by slug
$terms = get_terms( $taxonomy, ['orderby' => 'slug'] );
// Make sure we have terms before we continue
if ( !$terms )
return false;
// Because empty terms stuffs around with array keys, lets reset them
$terms = array_values( $terms );
// Lets get all the term id's from the array of term objects
$term_ids = wp_list_pluck( $terms, 'term_id' );
/**
* We now need to locate the position of the current term amongs the $term_ids array. \
* This way, we can now know which terms are adjacent to the current one
*/
$current_term_position = array_search( $current_term->term_id, $term_ids );
// Set default variables to hold the next and previous terms
$previous_term = '';
$next_term = '';
// Get the previous term
if ( 'previous' === $direction
|| !$direction
) {
if ( 0 === $current_term_position ) {
$previous_term = $terms[intval( count( $term_ids ) - 1 )];
} else {
$previous_term = $terms[$current_term_position - 1];
}
}
// Get the next term
if ( 'next' === $direction
|| !$direction
) {
if ( intval( count( $term_ids ) - 1 ) === $current_term_position ) {
$next_term = $terms[0];
} else {
$next_term = $terms[$current_term_position + 1];
}
}
$link = [];
// Build the links
if ( $previous_term )
$link[] = 'Previous Term: <a href="' . esc_url( get_term_link( $previous_term ) ) . '">' . $previous_term->name . '</a>';
if ( $next_term )
$link[] = 'Next Term: <a href="' . esc_url( get_term_link( $next_term ) ) . '">' . $next_term->name . '</a>';
return implode( ' ...|... ', $link );
}
You can use the code in three different ways
echo get_tax_navigation( 'podcast' ); to display next and previous terms
echo get_tax_navigation( 'podcast', 'previous' ); to display only the previous term
echo get_tax_navigation( 'podcast', 'next' ); to display only the next term
Something like this will do it, if you have a lot of terms it could be a rather expensive query though as it retrieves them all, can't see a way around that right now... (though you could cache all term results in a transient perhaps so it is not being done every pageload.)
function custom_term_navigation() {
$thistermid = get_queried_object()->term_id;
if (!is_numeric($thistermid)) {return;}
// remove commenting to use transient storage
// $terms = get_transient('all_podcast_terms');
// if (!$terms) {
$args = array('orderby'=>'slug');
$terms = get_terms('podcast',$args);
// set_transient('all_podcast_terms',$terms,60*60);
// }
$termid = ''; $termslug = ''; $foundterm = false;
foreach ($terms as $term) {
$prevterm = $termslug;
$termid = $term->term_id;
if ($foundterm) {$nextterm = $term->slug; break;}
if ($termid == $thistermid) {
$foundterm = true; $previousterm = $prevterm;
}
$termslug = $term->slug;
}
$navigation = '';
if ($previousterm != '') {
$previoustermlink = get_term_link($previousterm,'podcast');
$navigation .= "".$previoustermlink."' style='float:left; display:inline;'>← Previous Term</a>";
}
if ($nexterm != '') {
$nexttermlink = get_term_link($nexterm,'podcast');
$navigation .= "<a href='".$nextermlink."' style='float:right; display:inline;'>Next Term →</a>";
}
return $navigation;
}
get_term_link for URLs.