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WP_Tax_Query::transform_query( array $query, string $resulting_field )

Transforms a single query, from one field to another.

Description

Operates on the $query object by reference. In the case of error, $query is converted to a WP_Error object.

Parameters

$query

(array) (Required) The single query. Passed by reference.

$resulting_field

(string) (Required) The resulting field. Accepts 'slug', 'name', 'term_taxonomy_id', or 'term_id'. Default 'term_id'.

Source

File: wp-includes/class-wp-tax-query.php

public function transform_query( &$query, $resulting_field ) {
		if ( empty( $query['terms'] ) ) {
			return;
		}

		if ( $query['field'] == $resulting_field ) {
			return;
		}

		$resulting_field = sanitize_key( $resulting_field );

		// Empty 'terms' always results in a null transformation.
		$terms = array_filter( $query['terms'] );
		if ( empty( $terms ) ) {
			$query['terms'] = array();
			$query['field'] = $resulting_field;
			return;
		}

		$args = array(
			'get'                    => 'all',
			'number'                 => 0,
			'taxonomy'               => $query['taxonomy'],
			'update_term_meta_cache' => false,
			'orderby'                => 'none',
		);

		// Term query parameter name depends on the 'field' being searched on.
		switch ( $query['field'] ) {
			case 'slug':
				$args['slug'] = $terms;
				break;
			case 'name':
				$args['name'] = $terms;
				break;
			case 'term_taxonomy_id':
				$args['term_taxonomy_id'] = $terms;
				break;
			default:
				$args['include'] = wp_parse_id_list( $terms );
				break;
		}

		$term_query = new WP_Term_Query();
		$term_list  = $term_query->query( $args );

		if ( is_wp_error( $term_list ) ) {
			$query = $term_list;
			return;
		}

		if ( 'AND' === $query['operator'] && count( $term_list ) < count( $query['terms'] ) ) {
			$query = new WP_Error( 'inexistent_terms', __( 'Inexistent terms.' ) );
			return;
		}

		$query['terms'] = wp_list_pluck( $term_list, $resulting_field );
		$query['field'] = $resulting_field;
	}

Changelog

Version Description
3.2.0 Introduced.

© 2003–2019 WordPress Foundation
Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/classes/wp_tax_query/transform_query