Customizing WordPress Archives For Categories, Tags And Other Taxonomies

Customizing WordPress Archives For Categories, Tags And Other Taxonomies

• By Josh Pollock


• August 27th, 2014


• 
  
• 2 Comments



Most WordPress users are informed with tags and categories and with how to use them to classify their blog posts. If we use tradition post forms in WordPress, we competence need to classify them like categories and tags. Categories and tags are examples of taxonomies, and WordPress allows we to emanate as many tradition taxonomies as we want. These tradition taxonomies work like categories or tags, though are separate.




In this tutorial, we’ll explain tradition taxonomies and how to emanate them. We’ll also go over that template files in a WordPress thesis control a repository of built-in and tradition taxonomies, and some modernized techniques for customizing a duty of taxonomy archives.




Terminology




Before continuing, let’s get a vernacular straight. A taxonomy is a WordPress calm type, used essentially to classify calm of any other calm type. The dual taxonomies everybody is informed with are built in: categories and tags. We tend to call an particular posting of a tab a “tag,” though to be precise, we should impute to it as a “term” in a “tag” taxonomy. We flattering many always impute to equipment in a tradition taxonomy as “terms.”




Categories and tags paint a dual forms of taxonomies: hierarchical and non-hierarchical. Like categories, hierarchical taxonomies can have parent-child relations between terms in a taxonomy. For example, we competence have on your blog a “films” difficulty that has several child categories, with names like “foreign” and “domestic.” Custom taxonomies competence also be hierarchical, like categories, or non-hierarchical, like tags.






A tiny partial of a “WordPress Template Hierarchy”. (Source¹)

The repository of a taxonomy is a list of posts in a taxonomy that is automatically generated by WordPress. For example, this would be a page we see when we click on a difficulty couple and see all posts in that category. We’ll go over how to change a duty of these pages and learn that template files beget them.




How Tag, Category and Custom Taxonomy Archives Work




For any category, tab and tradition taxonomy, WordPress automatically generates an repository that lists any post compared with that taxonomy, in retreat sequential order. The complement works unequivocally good if we classify your blog posts with categories and tags. If we have a formidable complement of organizing tradition post forms with tradition taxonomies, afterwards it competence not be ideal. We’ll go over a many ways to cgange these archives.




The initial step to customizing is to know that files in your thesis are used to arrangement a archive. Different themes have opposite template files, though all themes have an index.php template. The index.php template is used to arrangement all content, unless a template exists aloft adult in a hierarchy. WordPress’ template hierarchy is a complement that dictates that template record is used to arrangement that content. We’ll quickly go over a template hierarchy for categories, tags and tradition taxonomies. If you’d like to learn more, these resources are rarely recommended:



• “Template Hierarchy²,” WordPress Codex


• “Template Hierarchy³,” Chip Bennett
  
  A upsurge chart


• The WordPress Template Hierarchy: A Mini Resource⁴, Rami Abraham and Michelle Schulp
  
  An interactive chart


• Reveal Template⁵, Scott Reilly
  
  A WordPress plugin



Most themes have an archive.php template, that is used for difficulty and tab archives, as good as date and author archives. You can supplement a template record to hoop difficulty and tab repository separately. These templates would be named category.php or tag.php, respectively. You could also emanate templates for specific tags or categories, regulating a ID or knock of a difficulty or tag. For example, a tab with a ID of 7 would use tag-7.php, if it exists, rather than tag.php or archive.php. A tab with a knock of “avocado” would be displayed regulating a tag-avocado.php template.




One wily thing to keep in mind is that a template named after a knock will overrule a template named after an ID number. So, if a tab with a knock of “avocado” had an ID of 7, afterwards tag-avocado.php would overrule tag-7.php, if it exists.




The template hierarchy for tradition taxonomies is a small different, since there are templates for all taxonomies, for specific taxonomies and for specific terms in a specific taxonomy. So, suppose that we have dual taxonomies, “fruits” and “vegetables,” and a “fruits” taxonomy has dual terms, “apples” and “oranges,” while “vegetables” has dual terms, “carrots” and “celery.” Let’s supplement 3 templates to a website’s theme: taxonomy.php, taxonomy-fruits.php and taxonomy-vegetables-carrots.php.




For a terms in a “fruits” taxonomy, all repository would be generated regulating taxonomy-fruits.php since no term-specific template exists. On a other hand, a tenure “carrots” in a “vegetables” taxonomy’s repository would be generated regulating taxonomy-vegetables-carrots.php. Because no taxonomy-vegetables.php template exists, all other terms in “vegetables” would be generated regulating taxonomy.php.




Using Conditional Tags




While we can supplement any of a tradition templates listed above to emanate a totally singular perspective for any category, tag, tradition taxonomy or tradition taxonomy term, infrequently all we wish to do is make one or dual small changes. In fact, try to equivocate formulating a lot of templates since we will need to adjust any one when we make altogether changes to a elementary HTML markup that we use in any template in a theme. Unless we need a template that is radically opposite from a theme’s archive.php, we tend to hang to adding redeeming changes to archive.php.




WordPress provides redeeming functions to establish possibly a category, tab or tradition taxonomy is being displayed. To establish possibly a difficulty repository is being shown, we can use is_category() for categories, is_tag() for tags and is_tax() for tradition taxonomies. The is_tag() and is_category() functions can also exam for specific categories or tags by knock or ID. For example:




?php
 if ( is_tag() ) 
 relate "True for any tag!";
 
 if ( is_tag( 'jedis' ) ) 
 relate "True for a tab whose knock is jedi";
 
 if ( is_tag( array( 'jedi', 'sith' ) ) ) 
 relate "True for tags whose knock is jedi or sith";
 
 if ( is_tag( 7 ) ) 
 relate "You can also use tab IDs. This is loyal for tab ID 7";
 
?




For tradition taxonomies, a is_tax() duty can be used to check possibly any taxonomy (not including categories and tags), a specific taxonomy or a specific tenure in a taxonomy is being shown. For example:




?php
 if ( is_tax() ) 
 relate "True for any tradition taxonomy.";
 
 if ( is_tax( 'vegetable' ) ) 
 relate "True for any tenure in a unfeeling taxonomy.";
 
 if ( is_tax( 'vegetable', 'celery' ) ) 
 relate "True usually for a tenure celery, in a unfeeling taxonomy.";
 
?




Creating Custom Taxonomies




Adding a tradition taxonomy can be finished in one of 3 ways: coding it manually according to a instructions in a Codex, that we don’t recommend; generating a formula regulating GenerateWP⁶; or regulating a plugin for tradition calm types, such as Pods⁷ or Types⁸. Plugins for tradition calm forms capacitate we to emanate tradition taxonomies and tradition post forms in WordPress’ behind finish though carrying to write any code. Using one is a easiest approach to supplement a tradition taxonomy and to get a horizon for operative with tradition calm types.




If we opt for one of a initial dual options, rather than a plugin, afterwards we will need to supplement a formula possibly to your theme’s functions.php record or to a tradition plugin. we strongly suggest formulating a tradition plugin, rather than adding a formula to functions.php. Even if you’ve never combined a plugin before, we titillate we to do it. While adding a formula to your theme’s functions.php will work, when we switch themes (say, since we wish to use a new thesis or to troubleshoot a problem), a taxonomy will no longer work.




Whether we write your tradition taxonomy formula by following a directions in a Codex or by generating it with GenerateWP, usually pulp it in a calm record and supplement one line of formula before it and you’ll have a plugin. Upload it and implement it as we would any other plugin.




The usually line we need to emanate a tradition plugin is /* Plugin name: Custom Taxonomy */.




Below is a plugin to register a tradition taxonomy named “vegetables,” that we combined regulating GenerateWP since it’s significantly easier and approach reduction expected to enclose errors than doing it manually:




?php
 /* Plugin Name: Veggie Taxonomy */
 if ( ! function_exists( 'slug_veggies_tax' ) ) 

 // Register Custom Taxonomy
 duty slug_veggies_tax() 

 $labels = array(
 'name' 	= _x( 'Vegetables', 'Taxonomy General Name', 'text_domain' ),
 'singular_name' 	= _x( 'Vegetable', 'Taxonomy Singular Name', 'text_domain' ),
 'menu_name' 	= __( 'Taxonomy', 'text_domain' ),
 'all_Veggies' = __( 'All Veggies', 'text_domain' ),
 'parent_Veggie' = __( 'Parent Veggie', 'text_domain' ),
 'parent_Veggie_colon' = __( 'Parent Veggie:', 'text_domain' ),
 'new_Veggie_name' = __( 'New Veggie name', 'text_domain' ),
 'add_new_Veggie' = __( 'Add new Veggie', 'text_domain' ),
 'edit_Veggie' = __( 'Edit Veggie', 'text_domain' ),
 'update_Veggie' = __( 'Update Veggie', 'text_domain' ),
 'separate_Veggies_with_commas' = __( 'Separate Veggies with commas', 'text_domain' ),
 'search_Veggies' = __( 'Search Veggies', 'text_domain' ),
 'add_or_remove_Veggies' = __( 'Add or mislay Veggies', 'text_domain' ),
 'choose_from_most_used' = __( 'Choose from a many used Veggies', 'text_domain' ),
 'not_found' = __( 'Not Found', 'text_domain' ),
 );
 $args = array(
 'labels' = $labels,
 'hierarchical' = false,
 'public' = true,
 'show_ui' = true,
 'show_admin_column' = true,
 'show_in_nav_menus' = true,
 'show_tagcloud' = false,
 );
 register_taxonomy( 'vegetable', array( 'post' ), $args );

 

 // Hook into a 'init' action
 add_action( 'init', 'slug_veggies_tax', 0 );

 
?




By a way, we combined this formula regulating GenerateWP in reduction than dual minutes! The use is great, and manually essay formula that this website can automatically beget for we creates no sense. To make a routine even easier, we can use a plugin Pluginception⁹ to emanate a vacant plugin for we and afterwards pulp a formula from GenerateWP into it regulating WordPress’ plugin editor.




Using WP_Query With Custom Taxonomies




Once we have combined a tradition taxonomy, we competence wish to query for posts with terms in that taxonomy. To do this, we can use taxonomy queries with WP_QUERY.




Taxonomy queries can be unequivocally elementary or complicated. The simplest query would be for all posts with a certain term. For example, if we had a post form named “jedi” and an compared tradition taxonomy named “level,” afterwards we could get all Jedi masters like this:




?php
 $args = array(
 'post_type' = 'jedi',
 'level' = 'master'
 );
 $query = new WP_Query( $args );
?




If we combined a second tradition taxonomy named “era,” afterwards we could find all Jedi masters of a Old Republic like this:




?php
 $args = array(
 'post_type' = 'jedi',
 'level' = 'master',
 'era' = 'old-republic',
 );
 $query = new WP_Query( $args );
?




We can also do some-more difficult comparisons, regulating a full tax_query. The tax_query evidence enables us to hunt by ID instead of knock (as we did before) and to hunt for some-more than one term. It also enables us to mix mixed taxonomy queries and to set a attribute between a two. In addition, we can even use SQL operators such as NOT IN to bar terms.




The possibilities are endless. Explore a “Taxonomy Parameters¹⁰” territory of a Codex page for “Class Reference/WP_Query” for finish information. The dash subsequent searches a “jedi” post form for Jedi knights and masters who are not from a Old Republic era:




?php
 $args = array(
 'post_type' = 'jedi',
 'tax_query' = array(
 'relation' = 'AND',
 array(
 'taxonomy' = 'level',
 'field' = 'slug',
 'terms' = array( 'master', 'knight' )
 ),
 array(
 'taxonomy' = 'era',
 'field' = 'slug',
 'terms' = array( 'old-republic' ),
 'operator' = 'NOT IN'
 )
 )
 );
 $query = new WP_Query( $args );
?




Customizing Taxonomy Archives




So far, we have lonesome how taxonomies, tags and categories work by default, as good as how to emanate tradition taxonomies. If any of this default duty doesn’t fit your needs, we can always cgange it. We’ll go over some ways to cgange WordPress’ built-in functionality for those of we who use WordPress reduction as a blogging height and some-more as a calm government system, that mostly requires tradition taxonomies.




Hello pre_get_posts




Before any posts are outputted by a WordPress loop, WordPress automatically retrieves a posts for a user according to a page they are on, regulating a WP_QUERY class. For example, in a categorical blog index, it gets a many new posts. In a taxonomy archive, it gets a many new posts in that taxonomy.




To change that query, we can use a pre_get_posts filter before WordPress gets any posts. This filter exposes a query intent after it is set though before it is used to indeed get any posts. This means that we can cgange a query regulating a difficulty methods before a categorical WordPress loop is run. If that sounds confusing, don’t worry — a subsequent few sections of this essay give unsentimental examples of how this works.




Adding Custom Post Types to Category or Tag Archives




A good use of modifying a WP_QUERY intent regulating pre_get_posts is to supplement posts from a tradition post form to a difficulty archive. By default, tradition post forms are not enclosed in this query. If we were constructing arguments to be upheld to WP_Query and wanted to embody both unchanging posts and posts in a tradition post form “jedi,” afterwards a evidence would demeanour like this:




?php
 $args = array( 'post_type' =
 array(
 'post',
 'jedi'
 )
 );
?




In a callback for a pre_get_posts filter, we need to pass a identical argument. The problem is that a WP_QUERY intent already exists, so we can’t pass an evidence to it like we do when formulating an instance of a class. Instead, we use a set() difficulty method, that allows us to change any of a arguments after a difficulty has been created.




In a dash below, we use set() to change a post_type evidence from a default value, that is post, to an array of post types, including posts and a tradition post form “jedi.” Note that we are regulating a redeeming tab is_category() so that a change happens usually when difficulty repository are being displayed.




?php
 add_filter( 'pre_get_posts', 'slug_cpt_category_archives' );
 duty slug_cpt_category_archives( $query ) 
 if ( $query-is_category() $query-is_main_query() ) 
 $query-set( 'post_type',
 array(
 'post',
 'jedi'
 )
 );
 

 lapse $query;

 
?




This function’s $query parameter is a WP_QUERY intent before it is used to stock a categorical loop. Because a page competence embody mixed loops, such as those used by widgets, we use a redeeming duty is_main_query() to safeguard that this affects usually a categorical loop and not any delegate loops on a page, such as those used by widgets.




Making Category or Hierarchical Taxonomy Archives Hierarchical




By default, a repository for categories and other hierarchical taxonomies act like any other taxonomy archive: they uncover all posts in that difficulty or with that taxonomy term. To uncover usually primogenitor terms and bar child terms, we would use a pre_get_posts filter again.




Just like when formulating your possess WP_QUERY for posts in a taxonomy, a categorical loop’s WP_QUERY uses a tax_query arguments to get posts by taxonomy. The tax_query has an include_children argument, that by default is set to 1 or true. By changing it to 0 or false, we can forestall posts with a child tenure from being enclosed in a archive:




?php
 add_action( 'pre_get_posts', 'slug_cpt_category_archives' );
 duty slug_cpt_category_archives( $query ) 
 if ( is_tax( 'TAXONOMY NAME') ) 
 $tax_query = $query-tax_query-queries;
 $tax_query['include_children'] = 0;
 $query-set( 'tax_query', $tax_query );
 

 
?




The outcome sounds fascinating though has several vital shortcomings. That’s OK, since if we residence those flaws, we’ll have taken a initial step to formulating something unequivocally cool.




The initial and biggest problem is that a outcome is not an repository page that shows a child terms; it’s still a post with a primogenitor term. The other problem is that we don’t have a good approach to navigate to a child tenure archives.




A good approach to understanding with this is to mix a pre_get_post filter above with a alteration to a template that shows a difficulty or taxonomy. We discussed progressing how to establish that template is used to outlay difficulty or tradition taxonomy archives. Also, keep in mind that we can always hang your changes in redeeming tags, such as is_category() or is_tax(), though that can turn unmanageable quickly; so, creation a duplicate of your archive.php and stealing any unneeded formula substantially creates some-more sense.




The initial step is to hang a whole thing in a check to see possibly a stream taxonomy tenure has children. If it does not, afterwards we do not wish to outlay anything. To do this, we use get_term_children(), that will lapse an dull array if a stream tenure has no children and that we can exam for with !empty().




To make this work for any taxonomy that competence be displayed, we need to get a stream taxonomy and taxonomy tenure from a query_vars array of a tellurian $wp_query object. The taxonomy’s knock is contained in a taxonomy key, and a term’s knock is in a tax key.




To use get_term_children(), we contingency have a term’s ID. The ID is not in query_vars, though we can pass a knock to get_term_by() to get it.




Here is how we get all of a information that we need into variables:




?php
 tellurian $wp_query;
 $taxonomy = $wp_query-query_vars['taxonomy'];
 $term = $wp_query-query_vars['tax'];
 $term_id = get_term_by( 'slug', $term, $taxonomy );
 $term_id = $term_id-term_id;
 $terms = get_term_children( $term_id, $taxonomy );
?




Now we will continue usually if $terms isn’t an dull array. To see possibly it is dull in a check, initial we will repopulate a terms regulating get_terms(). This is required since get_term_children earnings usually an array of IDs, and we need IDs and names, both of that are in a intent returned by get_terms(). We can loop by this object, outputting a name as a link. The couple can be generated by flitting a term’s ID to get_term_link().




Here is a finish code:




?php
 tellurian $wp_query;
 $taxonomy = $wp_query-query_vars['taxonomy'];
 $term = $wp_query-query_vars['tax'];
 $term_id = get_term_by( 'slug', $term, $taxonomy );
 $term_id = $term_id-term_id;
 $terms = get_term_children( $term_id, $taxonomy );
 if ( !empty( $terms ) ) {
 $terms = get_terms( $taxonomy, array( 'child_of' = $term_id ) );
 relate 'ul class="child-term-list"';
 foreach ( $terms as $term ) 
 relate 'lia href="'.$term-term_id.'"'.$term-name.'/a/li';
 

 relate '/ul';

?




Creating A Custom Landing Page For Taxonomy Archives




If your hierarchical taxonomy has no terms in a primogenitor term, afterwards a unchanging taxonomy repository complement will be of no use to you. You unequivocally wish to uncover taxonomy links instead.




In this case, a good choice is to emanate a tradition alighting page for a term. We’ll use query_vars again to establish possibly a user is on a initial page of a taxonomy archive; if so, we will use a taxonomy_archive filter to embody a apart template, like this:




?php
 add_filter( 'taxonomy_archive ', 'slug_tax_page_one' );
 duty slug_tax_page_one( $template ) 
 if ( is_tax( 'TAXONOMY_NAME' ) ) 
 tellurian $wp_query;
 $page = $wp_query-query_vars['paged'];
 if ( $page = 0 ) 
 $template = get_stylesheet_directory(). '/taxonomy-page-one.php';
 
 

 lapse $template;

 
?




This callback initial checks that a user is in a taxonomy that we wish to target. We can aim all taxonomies by changing this to usually is_tax(). Then, it gets a stream page regulating a query_var named paged, and if a user is on a initial page, afterwards it earnings a residence for a new template file. If not, it earnings a default template file.




What we put in that template record is adult to you. You can emanate a list of terms regulating a formula shown above. You can use it to outlay any content, unequivocally — for example, some-more information about a taxonomy tenure or links to specific posts.




Taking Control




With a bit of work, WordPress’ elementary architecture, that still reflects a origins as a blogging platform, can be customized to fit roughly any website or Web app. Using tradition taxonomies to classify your calm and doing it in a approach that suits your needs will be an critical step in many of your WordPress projects. Hopefully, this post has brought we a step closer to removing a many out of this absolute aspect of WordPress.




(dp, al, il)




Footnotes



1. 1 http://wphierarchy.com/


2. 2 https://codex.wordpress.org/Template_Hierarchy


3. 3 http://www.chipbennett.net/themes/template-hierarchy/


4. 4 http://wphierarchy.com/


5. 5 https://wordpress.org/plugins/reveal-template/


6. 6 http://generatewp.com/


7. 7 http://pods.io


8. 8 http://wp-types.com/home/types-manage-post-types-taxonomy-and-custom-fields/


9. 9 https://wordpress.org/plugins/pluginception/


10. 10 http://codex.wordpress.org/Class_Reference/WP_Query#Taxonomy_Parameters



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Customizing WordPress Archives For Categories, Tags And Other Taxonomies