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WordPress Term Hierarchical Search
<?php
/**
* Term Hierarchical Search
*
* These methods provide a utility interface to find a meta value
* within the term's hierarchy. It walks up the hierarchy starting
* at the given term, i.e. walks to its parent -> grandparent -> N levels.
*
* It's performant as it grabs the records it needs out of the database
* with one SQL query, i.e. to avoid multiple trips to gather each level's
* record and then metadata.
*
* @package KnowTheCode\TermHierarchicalSearch
* @since 1.0.0
* @author hellofromTonya
* @link https://KnowTheCode.io
* @license GNU-2.0+
*/
namespace KnowTheCode\TermHierarchicalSearch;
use WP_Term;
/**
* Get the metadata value for the term. This function walks up the term hierarchy,
* searching each parent level to find a value for the given meta key. When it finds
* one, it's returned.
*
* To perform an archive settings check, turn on the $check_for_archive_setting flag to
* true. This extra check does the following:
*
* 1. Checks each level's `enable_content_archive_settings` value.
* 2. If it's enabled, then that level's meta value is returned, regardless if
* it has a value or not.
*
* It works a level override, forcing that level to return it's value.
*
* @since 1.0.0
*
* @param WP_Term $term Term object
* @param string $meta_key Meta key for the value you want to retrieve
* @param bool $check_for_archive_setting Flag to check if the `enable_content_archive_settings`
* is set. When TRUE, check if this flag is set.
*
* @return mixed
*/
function get_term_meta_value_in_hierarchy( WP_Term $term, $meta_key, $check_for_archive_setting = false ) {
$meta_keys = array( $meta_key );
if ( $check_for_archive_setting ) {
$meta_keys[] = 'enable_content_archive_settings';
}
$term_ancestors = get_hierarchichal_term_metadata( $term, $meta_keys );
if ( $term_ancestors === false ) {
return;
}
// Loop through the objects until you find one that has a meta value.
foreach( (array) $term_ancestors as $term_ancestor ) {
// When enabled, check to see if the content archive setting is turned on.
if ( $check_for_archive_setting && $term_ancestor->metadata2 ) {
return $term_ancestor->metadata1;
}
if ( $term_ancestor->metadata1 ) {
return $term_ancestor->metadata1;
}
}
// Whoops, didn't find one with a value for that meta key.
return;
}
/**
* Get the specified metadata value for the term or from
* one of it's parent terms.
*
* @since 1.0.0
*
* @param WP_Term $term Term object
* @param string|array $meta_key The meta key(s) to retrieve.
*
* @return mixed|null
*/
function get_hierarchichal_term_metadata( WP_Term $term, $meta_key ) {
if ( ! is_taxonomy_hierarchical( $term->taxonomy ) ) {
return;
}
if ( ! has_parent_term( $term ) ) {
return;
}
return get_terms_ancestory_tree( $term->term_id, $meta_key );
}
/**
* Get an array of term ancestors for the given term id, meaning
* the SQL query starts at the given term id and then walks up
* the parent tree as it stores the columns.
*
* The result is an array of stdClass objects that have the following:
* term_id => int
* parent_id => int
* metadata1 => value of that meta key's column
* ..
* metadataN => value of the meta key #N
*
* @since 1.0.0
*
* @param integer $term_id
* @param array $meta_keys Array of meta key(s) to retrieve.
*
* @return array|bool
*/
function get_terms_ancestory_tree( $term_id, array $meta_keys ) {
global $wpdb;
// Build the SQL Query first.
$sql_query = build_terms_ancestory_tree_sql_query( $meta_keys );
// Assemble the values, i.e. get them in the right order
// to insert into the SQL query.
$values = $meta_keys;
array_unshift( $values, $term_id );
// Prepare the values and then insert into the SQL query.
// We are swapping out the %d/%f/%s placeholders with their value.
$sql_query = $wpdb->prepare( $sql_query, $values );
// Run the query to get records from the database.
$records = $wpdb->get_results( $sql_query );
// Check if we got records back from the database. If yes,
// return the records.
if ( $records && is_array( $records ) ) {
return $records;
}
// Oh poo, we something when wrong.
return false;
}
/**
* Build the SQL Query string.
*
* @since 1.0.0
*
* @param array $meta_keys Array of meta key(s) to retrieve.
*
* @return string
*/
function build_terms_ancestory_tree_sql_query( array $meta_keys ) {
global $wpdb;
$number_of_meta_keys = count( $meta_keys );
$sql_query = "SELECT t.term_id, @parent := t.parent AS parent_id";
for( $suffix_number = 1; $suffix_number <= $number_of_meta_keys; $suffix_number++ ) {
$sql_query .= sprintf( ', tm%1$d.meta_value AS metadata%1$d', $suffix_number );
}
$sql_query .= "\n" .
"FROM (
SELECT *
FROM {$wpdb->term_taxonomy} AS tt
ORDER BY
CASE
WHEN tt.term_id > tt.parent THEN tt.term_id
ELSE tt.parent
END DESC
) AS t
JOIN (
SELECT @parent := %d
) AS tmp";
for( $suffix_number = 1; $suffix_number <= $number_of_meta_keys; $suffix_number++ ) {
$sql_query .= "\n" . sprintf(
'LEFT JOIN %1$s AS tm%2$d ON tm%2$d.term_id = @parent AND tm%2$d.meta_key = ',
$wpdb->termmeta,
$suffix_number
);
$sql_query .= '%s';
}
$sql_query .= "\n" . "WHERE t.term_id = @parent;";
return $sql_query;
}
/**
* Checks if the term has a parent.
*
* @since 1.0.0
*
* @param WP_Term $term Term object.
*
* @return bool
*/
function has_parent_term( WP_Term $term ) {
return ( $term->parent > 0 );
}
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