WP_Tax_Query::sanitize_query( array $queries ): array

136	public function sanitize_query( $queries ) {137		$cleaned_query = array();138 139		$defaults = array(140			'taxonomy'         => '',141			'terms'            => array(),142			'field'            => 'term_id',143			'operator'         => 'IN',144			'include_children' => true,145		);146 147		foreach ( $queries as $key => $query ) {148			if ( 'relation' === $key ) {149				$cleaned_query['relation'] = $this->sanitize_relation( $query );150 151				// First-order clause.152			} elseif ( self::is_first_order_clause( $query ) ) {153 154				$cleaned_clause          = array_merge( $defaults, $query );155				$cleaned_clause['terms'] = (array) $cleaned_clause['terms'];156				$cleaned_query[]         = $cleaned_clause;157 158				/*159				 * Keep a copy of the clause in the flate160				 * $queried_terms array, for use in WP_Query.161				 */162				if ( ! empty( $cleaned_clause['taxonomy'] ) && 'NOT IN' !== $cleaned_clause['operator'] ) {163					$taxonomy = $cleaned_clause['taxonomy'];164					if ( ! isset( $this->queried_terms[ $taxonomy ] ) ) {165						$this->queried_terms[ $taxonomy ] = array();166					}167 168					/*169					 * Backward compatibility: Only store the first170					 * 'terms' and 'field' found for a given taxonomy.171					 */172					if ( ! empty( $cleaned_clause['terms'] ) && ! isset( $this->queried_terms[ $taxonomy ]['terms'] ) ) {173						$this->queried_terms[ $taxonomy ]['terms'] = $cleaned_clause['terms'];174					}175 176					if ( ! empty( $cleaned_clause['field'] ) && ! isset( $this->queried_terms[ $taxonomy ]['field'] ) ) {177						$this->queried_terms[ $taxonomy ]['field'] = $cleaned_clause['field'];178					}179				}180 181				// Otherwise, it's a nested query, so we recurse.182			} elseif ( is_array( $query ) ) {183				$cleaned_subquery = $this->sanitize_query( $query );184 185				if ( ! empty( $cleaned_subquery ) ) {186					// All queries with children must have a relation.187					if ( ! isset( $cleaned_subquery['relation'] ) ) {188						$cleaned_subquery['relation'] = 'AND';189					}190 191					$cleaned_query[] = $cleaned_subquery;192				}193			}194		}195 196		return $cleaned_query;197	}