Goodbye `get_terms`, Welcome `WP_Term_Query`

From WordPress 4.6, we have a new class called ​WP_Term_Query which will help us in querying the taxonomies easily.

This class will give us more flexibility and ease of use like other classes like WP_Query,WP_User_Query, and WP_Comment_Query in WordPress. The main benefit is the caching and security measures. So you don’t need to write complex and insecure SQL queries.

Sample Code:

$term_query = new WP_Term_Query( $args );
if ( ! empty( $term_query->terms ) ) {
    foreach ( $term_query->terms as $term ) {
        echo $term->name;
    }
} else {
    echo 'No term found.';
}

We can pass custom query parameters via $args array.

Parameters:

• ‘taxonomy’
  (string|array) Taxonomy name, or array of taxonomies, to which results should be limited.
• ‘orderby’
  (string) Field(s) to order terms by. Accepts term fields (‘name’, ‘slug’, ‘term_group’, ‘term_id’, ‘id’, ‘description’), ‘count’ for term taxonomy count, ‘include’ to match the ‘order’ of the $include param, ‘meta_value’, ‘meta_value_num’, the value of $meta_key, the array keys of $meta_query, or ‘none’ to omit the ORDER BY clause. Defaults to ‘name’.
• ‘order’
  (string) Whether to order terms in ascending or descending order. Accepts ‘ASC’ (ascending) or ‘DESC’ (descending). Default ‘ASC’.
• ‘hide_empty’
  (bool|int) Whether to hide terms not assigned to any posts. Accepts 1|true or 0|false. Default 1|true.
• ‘include’
  (array|string) Array or comma/space-separated string of term ids to include.
• ‘exclude’
  (array|string) Array or comma/space-separated string of term ids to exclude. If $include is non-empty, $exclude is ignored.
• ‘exclude_tree’
  (array|string) Array or comma/space-separated string of term ids to exclude along with all of their descendant terms. If $include is non-empty, $exclude_tree is ignored.
• ‘number’
  (int|string) Maximum number of terms to return. Accepts ”|0 (all) or any positive number. Default ”|0 (all).
• ‘offset’
  (int) The number by which to offset the terms query.
• ‘fields’
  (string) Term fields to query for. Accepts ‘all’ (returns an array of complete term objects), ‘ids’ (returns an array of ids), ‘id=>parent’ (returns an associative array with ids as keys, parent term IDs as values), ‘names’ (returns an array of term names), ‘count’ (returns the number of matching terms), ‘id=>name’ (returns an associative array with ids as keys, term names as values), or ‘id=>slug’ (returns an associative array with ids as keys, term slugs as values). Default ‘all’.
• ‘name’
  (string|array) Optional. Name or array of names to return term(s) for.
• ‘slug’
  (string|array) Optional. Slug or array of slugs to return term(s) for.
• ‘hierarchical’
  (bool) Whether to include terms that have non-empty descendants (even if $hide_empty is set to true). Default true.
• ‘search’
  (string) Search criteria to match terms. Will be SQL-formatted with wildcards before and after.
• ‘name__like’
  (string) Retrieve terms with criteria by which a term is LIKE $name__like.
• ‘description__like’
  (string) Retrieve terms where the description is LIKE $description__like.
• ‘pad_counts’
  (bool) Whether to pad the quantity of a term’s children in the quantity of each term’s “count” object variable. Default false.
• ‘get’
  (string) Whether to return terms regardless of ancestry or whether the terms are empty. Accepts ‘all’ or empty (disabled).
• ‘child_of’
  (int) Term ID to retrieve child terms of. If multiple taxonomies are passed, $child_of is ignored. Default 0.
• ‘parent’
  (int|string) Parent term ID to retrieve direct-child terms of.
• ‘childless’
  (bool) True to limit results to terms that have no children. This parameter has no effect on non-hierarchical taxonomies. Default false.
• ‘cache_domain’
  (string) Unique cache key to be produced when this query is stored in an object cache. Default is ‘core’.
• ‘update_term_meta_cache’
  (bool) Whether to prime meta caches for matched terms. Default true.
• ‘meta_query’
  (array) Meta query clauses to limit retrieved terms by. See WP_Meta_Query.
• ‘meta_key’
  (string) Limit terms to those matching a specific metadata key. Can be used in conjunction with $meta_value.
• ‘meta_value’
  (string) Limit terms to those matching a specific metadata value. Usually used in conjunction with $meta_key.

Sample Code:

$term_query = new WP_Term_Query( array( 'taxonomy' => 'category' ) );
if ( ! empty( $term_query->terms ) ) {
    foreach ( $term_query->terms as $term ) {
        echo $term->name;
    }
} else {
    echo 'No term found.';
}