How can I get only parent terms?

Is there any way to get only parent terms from custom taxonomy or category?

Answers:

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Method 1

Yes, just pass in the parent parameter to get_terms when you call it, as Michael pointed out.

Since WP 4.5 this is the recommend usage:

$myterms = get_terms( array( 'taxonomy' => 'taxonomy_name', 'parent' => 0 ) );

Prior to WP 4.5 this was the default usage:

$myterms = get_terms( 'taxonomy_name_here', array( 'parent' => 0 ) );

Will return all terms that have a parent value of 0, ie. top level terms.

Method 2

use the ‘parent’ parameter:

http://codex.wordpress.org/Function_Reference/get_terms

or

http://codex.wordpress.org/Function_Reference/get_categories

Method 3

for woocommerce email templates use the following:

$terms = get_the_terms( $_product->id , 'product_cat');
    if($terms) {
        foreach( $terms as $term ) {
            $term = get_term_by("id", $term->parent, "product_cat");
            if ($term->parent > 0) {
                $term = get_term_by("id", $term->parent, "product_cat");
            }
            $cat_obj = get_term($term->term_id, 'product_cat');
            $cat_name = $cat_obj->name;
        }
    }
echo '<br />('. $cat_name . ')';

Method 4

 $archive_cats= get_terms( 'archivecat', 'orderby=count&hide_empty=0&parent=0' );

Method 5

For this demonstration, we will assume that we have a taxonomy called “Books”.
And we might have a hierarchy of:

Fiction (id: 699)
 - This is a Fiction Story.
Non-Fiction
 - Title of Non-fiction
Fantasy
  -  ...

We want to get the parent term of the taxonomy “Books” of the current post.

/* Get the Parent Taxonomy Term Name by post Id */

function get_parent_term_by_post_id($taxname, $taxid=null){

if(isset($taxid)):

    //Get by term Id passed in function
    $parent_tax = get_term_by('id', $taxid, $taxname);

    return $parent_tax ->name; //use name, slug, or id

else:

     //Get by PostId of current page
     $terms = wp_get_post_terms( get_the_id(), $taxname);

     $tax_parent_id = $terms[0]->parent;

     if($tax_parent_id == 0):
      $tax_parent_id = $terms[0]->parent; //get the next parent ID
     endif; 

     $parent_tax = get_term_by('id', $tax_parent_id , $taxname);

     return $parent_tax ->name; //use name, slug, or id

endif;

}

Then you just run on you template like this:

//enter custom tax name. will grab by post id 
echo get_parent_term_name_by_post_id('books'); //returns Fiction

or

//by term ID 
echo get_parent_term_name_by_post_id('books', 699); //returns Fiction

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0