How To Get Parent Category Slug of Current Post

9 comments

1. You will need to use the ID value returned by $category[0]->category_parent and pass it through get_term(). Example:

   $category = get_the_category(); 
   $category_parent_id = $category[0]->category_parent;
   if ( $category_parent_id != 0 ) {
       $category_parent = get_term( $category_parent_id, 'category' );
       $css_slug = $category_parent->slug;
   } else {
       $css_slug = $category[0]->slug;
   }
   

2. You will need to query for the parent category data. get_category is pretty much built for doing that.

   $category = get_the_category(); 
   $parent = get_category($category[0]->category_parent);
   echo $parent->slug;
   

   That will return the immediate parent of the category. That is given this set of categories:

   • Cartoon
     • Dog
       • Scooby

   The code above will return “Dog” if you give it the ID for “Scooby”. If you want the topmost parent category– “Cartoon”– no matter how deep the nesting, use something like this:

   $category = get_the_category(); 
   $parent = get_ancestors($category[0]->term_id,'category');
   if (empty($parent)) {
     $parent[] = array($category[0]->term_id);
   }
   $parent = array_pop($parent);
   $parent = get_category($parent); 
   if (!is_wp_error($parent)) {
     var_dump($parent);
   } else {
     echo $parent->get_error_message();
   }
   

   That also has the advantage of relatively neat error handling.

3. I found most of the above did not work for Custom Post Types. So I wrote the following function.

   Given the ID of the current ( child ) category, it works its way up the chain to give the parent(s) of the category.
   It returns an array containing url, name, slug and id of parents.

   /**
    * @param $category_id
    *
    * @return array        Returns either empty array if no parents or
    *                      an array of  categories from base category[0] to parent category
    *                      The array has a sub array of ['id'] ['name'] ['slug'] ['url']
    *
    */
   
   function get_category_parent_array( $category_id, $category_taxonomy = 'category'){
   
       $category_id = abs((int)$category_id);
       $category_taxonomy = sanitize_key( $category_taxonomy);
       
       // Sanity check for top parent - ( id = 0 )
       if( 0 == $category_id ){
           return array();
       }
   
       $child_category = get_term( $category_id, $category_taxonomy);
       if( empty($child_category)){
           return array();
       }
   
       $parent_category_id = $child_category->parent;
       if( 0 == $parent_category_id ){
           return array(); // We cant get category 0.
       }
   
   
       // We have checked if the parent_id is 0 but double check here for other issues causing empty parent category
       $parent_category = get_term( $parent_category_id, $category_taxonomy);
       if ( empty ( $parent_category ) ){
           return array();
       }
   
       // Prepare the return array
       $parent_array = array();
   
       $parent_array['id'] =   $parent_category_id;
       $parent_array['slug'] = esc_attr($parent_category->slug);
       $parent_array['name'] = esc_attr($parent_category->name);
       $parent_array['url'] =  esc_url(get_term_link( $parent_category));
   
       if ( 0 == $parent_category_id ){
           return $parent_array;
       }else{
           $new_parent = get_category_parent_array($parent_category_id, $category_taxonomy );
           if(! empty( $new_parent ) ){
               return array( $new_parent, $parent_array);
           }else{
               return $parent_array;
           }
   
       }
   
   }
   

   For example. In a tree of Home>Products>Platic-Bags>Poly-Bags>3muBags
   Where the child / current category is 3mu it returned the following:

   array (
     0 => 
     array (
       'id' => 260,
       'slug' => 'plastic-bags',
       'name' => 'Plastic Bags',
       'url' => 'https://example.com/product_category/plastic-bags/',
     ),
     1 => 
     array (
       'id' => 261,
       'slug' => 'polybags',
       'name' => 'Polybags',
       'url' => 'https://exmapl.com/product_category/polybags/',
     ),
   );
   
   

4. I like the previous answer from @s_ha_dum, but for getting the top-level category regardless of depth, I used what I consider to be a simpler solution:

   $cats = get_the_category();
   foreach ( $cats as $cat ) {
       if ( $cat->category_parent == 0 ) {
           return $cat->name; // ...or whatever other attribute/processing you want
       }
   }
   return ''; // This was from a shortcode; adjust the return value to taste
   

5. If it can help somebody… to get child cat or parent, depending on the 0 or 1 you put on the $category

   $category = get_the_category();
   $parent = get_cat_name( $category[0]->category_parent );
   if( ! function_exists('get_cat_slug') )
   {
       function get_cat_slug($cat_id) {
           $cat_id = (int) $cat_id;
           $category = &get_category($cat_id);
           return $category->slug;
       }
   }
   if ( !empty($parent) ) {
       $output .= '<H2>' . esc_html( $category[1]->name ) . '</H2>';                               
   } else {
       $output .= '<H2>' . esc_html( $category[0]->name ) . '</H2';
   }
   

6. You can simplify it like this:

     $category   = get_the_category();
     $cat_parent = $category[0]->category_parent;
     $category   = $cat_parent != 0 ? get_term($cat_parent, 'category')->slug : $category[0]->slug;
   

7. The following function is adapted to return the root category:

   function get_root_category($category = null) {
     if (!$category) $category = get_the_category()[0];
     $ancestors = get_ancestors($category->term_id, 'category');
     if (empty($ancestors)) return $category;
     $root = get_category(array_pop($ancestors)); 
     return $root;
   }
   

   Usage:
   get_root_category()->slug

8. All the answers above are good except the “category_parent” now replaced with “parent” from 2018!

   In 2021

   $custom_tax = 'books_category'; //Custom taxonomy
   
   //Get the terms from post ID
   $terms = get_the_terms( $post->ID, $custom_tax );
   $parent_id = $terms[0]->parent;
   
   if ($parent_id != 0){
       $parent = get_term( $parent_id, $custom_tax);
       echo $parent->slug;
   }
   

9. For Taxonomies in 2021

   $capitulos = get_the_terms( $post->ID, 'capitulos' );
   if ($capitulos) {
   foreach($capitulos as $capitulo) { if ($capitulo->parent == 0) 
   echo '<a href="' . get_term_link($capitulo->term_id) . '">' . $capitulo->name . '</a> ';}
   }
   

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