first-order.
	 *
	 * A first-order meta query clause is one that has either a 'key' or
	 * a 'value' array key.
	 *
	 * @since 4.1.0
	 *
	 * @param array $query Meta query arguments.
	 * @return bool Whether the query clause is a first-order clause.
	 */
	protected function is_first_order_clause( $query ) {
		return isset( $query['key'] ) || isset( $query['value'] );
	}

	/**
	 * Constructs a meta query based on 'meta_*' query vars
	 *
	 * @since 3.2.0
	 *
	 * @param array $qv The query variables.
	 */
	public function parse_query_vars( $qv ) {
		$meta_query = array();

		/*
		 * For orderby=meta_value to work correctly, simple query needs to be
		 * first (so that its table join is against an unaliased meta table) and
		 * needs to be its own clause (so it doesn't interfere with the logic of
		 * the rest of the meta_query).
		 */
		$primary_meta_query = array();
		foreach ( array( 'key', 'compare', 'type', 'compare_key', 'type_key' ) as $key ) {
			if ( ! empty( $qv[ "meta_$key" ] ) ) {
				$primary_meta_query[ $key ] = $qv[ "meta_$key" ];
			}
		}

		// WP_Query sets 'meta_value' = '' by default.
		if ( isset( $qv['meta_value'] ) && '' !== $qv['meta_value'] && ( ! is_array( $qv['meta_value'] ) || $qv['meta_value'] ) ) {
			$primary_meta_query['value'] = $qv['meta_value'];
		}

		$existing_meta_query = isset( $qv['meta_query'] ) && is_array( $qv['meta_query'] ) ? $qv['meta_query'] : array();

		if ( ! empty( $primary_meta_query ) && ! empty( $existing_meta_query ) ) {
			$meta_query = array(
				'relation' => 'AND',
				$primary_meta_query,
				$existing_meta_query,
			);
		} elseif ( ! empty( $primary_meta_query ) ) {
			$meta_query = array(
				$primary_meta_query,
			);
		} elseif ( ! empty( $existing_meta_query ) ) {
			$meta_query = $existing_meta_query;
		}

		$this->__construct( $meta_query );
	}

	/**
	 * Returns the appropriate alias for the given meta type if applicable.
	 *
	 * @since 3.7.0
	 *
	 * @param string $type MySQL type to cast meta_value.
	 * @return string MySQL type.
	 */
	public function get_cast_for_type( $type = '' ) {
		if ( empty( $type ) ) {
			return 'CHAR';
		}

		$meta_type = strtoupper( $type );

		if ( ! preg_match( '/^(?:BINARY|CHAR|DATE|DATETIME|SIGNED|UNSIGNED|TIME|NUMERIC(?:\(\d+(?:,\s?\d+)?\))?|DECIMAL(?:\(\d+(?:,\s?\d+)?\))?)$/', $meta_type ) ) {
			return 'CHAR';
		}

		if ( 'NUMERIC' === $meta_type ) {
			$meta_type = 'SIGNED';
		}

		return $meta_type;
	}

	/**
	 * Generates SQL clauses to be appended to a main query.
	 *
	 * @since 3.2.0
	 *
	 * @param string $type              Type of meta. Possible values include but are not limited
	 *                                  to 'post', 'comment', 'blog', 'term', and 'user'.
	 * @param string $primary_table     Database table where the object being filtered is stored (eg wp_users).
	 * @param string $primary_id_column ID column for the filtered object in $primary_table.
	 * @param object $context           Optional. The main query object that corresponds to the type, for
	 *                                  example a `WP_Query`, `WP_User_Query`, or `WP_Site_Query`.
	 *                                  Default null.
	 * @return string[]|false {
	 *     Array containing JOIN and WHERE SQL clauses to append to the main query,
	 *     or false if no table exists for the requested meta type.
	 *
	 *     @type string $join  SQL fragment to append to the main JOIN clause.
	 *     @type string $where SQL fragment to append to the main WHERE clause.
	 * }
	 */
	public function get_sql( $type, $primary_table, $primary_id_column, $context = null ) {
		$meta_table = _get_meta_table( $type );
		if ( ! $meta_table ) {
			return false;
		}

		$this->table_aliases = array();

		$this->meta_table     = $meta_table;
		$this->meta_id_column = sanitize_key( $type . '_id' );

		$this->primary_table     = $primary_table;
		$this->primary_id_column = $primary_id_column;

		$sql = $this->get_sql_clauses();

		/*
		 * If any JOINs are LEFT JOINs (as in the case of NOT EXISTS), then all JOINs should
		 * be LEFT. Otherwise posts with no metadata will be excluded from results.
		 */
		if ( str_contains( $sql['join'], 'LEFT JOIN' ) ) {
			$sql['join'] = str_replace( 'INNER JOIN', 'LEFT JOIN', $sql['join'] );
		}

		/**
		 * Filters the meta query's generated SQL.
		 *
		 * @since 3.1.0
		 *
		 * @param string[] $sql               Array containing the query's JOIN and WHERE clauses.
		 * @param array    $queries           Array of meta queries.
		 * @param string   $type              Type of meta. Possible values include but are not limited
		 *                                    to 'post', 'comment', 'blog', 'term', and 'user'.
		 * @param string   $primary_table     Primary table.
		 * @param string   $primary_id_column Primary column ID.
		 * @param object   $context           The main query object that corresponds to the type, for
		 *                                    example a `WP_Query`, `WP_User_Query`, or `WP_Site_Query`.
		 */
		return apply_filters_ref_array( 'get_meta_sql', array( $sql, $this->queries, $type, $primary_table, $primary_id_column, $context ) );
	}

	/**
	 * Generates SQL clauses to be appended to a main query.
	 *
	 * Called by the public WP_Meta_Query::get_sql(), this method is abstracted
	 * out to maintain parity with the other Query classes.
	 *
	 * @since 4.1.0
	 *
	 * @return string[] {
	 *     Array containing JOIN and WHERE SQL clauses to append to the main query.
	 *
	 *     @type string $join  SQL fragment to append to the main JOIN clause.
	 *     @type string $where SQL fragment to append to the main WHERE clause.
	 * }
	 */
	protected function get_sql_clauses() {
		/*
		 * $queries are passed by reference to get_sql_for_query() for recursion.
		 * To keep $this->queries unaltered, pass a copy.
		 */
		$queries = $this->queries;
		$sql     = $this->get_sql_for_query( $queries );

		if ( ! empty( $sql['where'] ) ) {
			$sql['where'] = ' AND ' . $sql['where'];
		}

		return $sql;
	}

	/**
	 * Generates SQL clauses for a single query array.
	 *
	 * If nested subqueries are found, this method recurses the tree to
	 * produce the properly nested SQL.
	 *
	 * @since 4.1.0
	 *
	 * @param array $query Query to parse (passed by reference).
	 * @param int   $depth Optional. Number of tree levels deep we currently are.
	 *                     Used to calculate indentation. Default 0.
	 * @return string[] {
	 *     Array containing JOIN and WHERE SQL clauses to append to a single query array.
	 *
	 *     @type string $join  SQL fragment to append to the main JOIN clause.
	 *     @type string $where SQL fragment to append to the main WHERE clause.
	 * }
	 */
	protected function get_sql_for_query( &$query, $depth = 0 ) {
		$sql_chunks = array(
			'join'  => array(),
			'where' => array(),
		);

		$sql = array(
			'join'  => '',
			'where' => '',
		);

		$indent = '';
		for ( $i = 0; $i < $depth; $i++ ) {
			$indent .= '  ';
		}

		foreach ( $query as $key => &$clause ) {
			if ( 'relation' === $key ) {
				$relation = $query['relation'];
			} elseif ( is_array( $clause ) ) {

				// This is a first-order clause.
				if ( $this->is_first_order_clause( $clause ) ) {
					$clause_sql = $this->get_sql_for_clause( $clause, $query, $key );

					$where_count = count( $clause_sql['where'] );
					if ( ! $where_count ) {
						$sql_chunks['where'][] = '';
					} elseif ( 1 === $where_count ) {
						$sql_chunks['where'][] = $clause_sql['where'][0];
					} else {
						$sql_chunks['where'][] = '( ' . implode( ' AND ', $clause_sql['where'] ) . ' )';
					}

					$sql_chunks['join'] = array_merge( $sql_chunks['join'], $clause_sql['join'] );
					// This is a subquery, so we recurse.
				} else {
					$clause_sql = $this->get_sql_for_query( $clause, $depth + 1 );

					$sql_chunks['where'][] = $clause_sql['where'];
					$sql_chunks['join'][]  = $clause_sql['join'];
				}
			}
		}

		// Filter to remove empties.
		$sql_chunks['join']  = array_filter( $sql_chunks['join'] );
		$sql_chunks['where'] = array_filter( $sql_chunks['where'] );

		if ( empty( $relation ) ) {
			$relation = 'AND';
		}

		// Filter duplicate JOIN clauses and combine into a single string.
		if ( ! empty( $sql_chunks['join'] ) ) {
			$sql['join'] = implode( ' ', array_unique( $sql_chunks['join'] ) );
		}

		// Generate a single WHERE clause with proper brackets and indentation.
		if ( ! empty( $sql_chunks['where'] ) ) {
			$sql['where'] = '( ' . "\n  " . $indent . implode( ' ' . "\n  " . $indent . $relation . ' ' . "\n  " . $indent, $sql_chunks['where'] ) . "\n" . $indent . ')';
		}

		return $sql;
	}

	/**
	 * Generates SQL JOIN and WHERE clauses for a first-order query clause.
	 *
	 * "First-order" means that it's an array with a 'key' or 'value'.
	 *
	 * @since 4.1.0
	 *
	 * @global wpdb $wpdb WordPress database abstraction object.
	 *
	 * @param array  $clause       Query clause (passed by reference).
	 * @param array  $parent_query Parent query array.
	 * @param string $clause_key   Optional. The array key used to name the clause in the original `$meta_query`
	 *                             parameters. If not provided, a key will be generated automatically.
	 *                             Default empty string.
	 * @return array {
	 *     Array containing JOIN and WHERE SQL clauses to append to a first-order query.
	 *
	 *     @type string[] $join  Array of SQL fragments to append to the main JOIN clause.
	 *     @type string[] $where Array of SQL fragments to append to the main WHERE clause.
	 * }
	 */
	public function get_sql_for_clause( &$clause, $parent_query, $clause_key = '' ) {
		global $wpdb;

		$sql_chunks = array(
			'where' => array(),
			'join'  => array(),
		);

		if ( isset( $clause['compare'] ) ) {
			$clause['compare'] = strtoupper( $clause['compare'] );
		} else {
			$clause['compare'] = isset( $clause['value'] ) && is_array( $clause['value'] ) ? 'IN' : '=';
		}

		$non_numeric_operators = array(
			'=',
			'!=',
			'LIKE',
			'NOT LIKE',
			'IN',
			'NOT IN',
			'EXISTS',
			'NOT EXISTS',
			'RLIKE',
			'REGEXP',
			'NOT REGEXP',
		);

		$numeric_operators = array(
			'>',
			'>=',
			'<',
			'<=',
			'BETWEEN',
			'NOT BETWEEN',
		);

		if ( ! in_array( $clause['compare'], $non_numeric_operators, true ) && ! in_array( $clause['compare'], $numeric_operators, true ) ) {
			$clause['compare'] = '=';
		}

		if ( isset( $clause['compare_key'] ) ) {
			$clause['compare_key'] = strtoupper( $clause['compare_key'] );
		} else {
			$clause['compare_key'] = isset( $clause['key'] ) && is_array( $clause['key'] ) ? 'IN' : '=';
		}

		if ( ! in_array( $clause['compare_key'], $non_numeric_operators, true ) ) {
			$clause['compare_key'] = '=';
		}

		$meta_compare     = $clause['compare'];
		$meta_compare_key = $clause['compare_key'];

		// First build the JOIN clause, if one is required.
		$join = '';

		// We prefer to avoid joins if possible. Look for an existing join compatible with this clause.
		$alias = $this->find_compatible_table_alias( $clause, $parent_query );
		if ( false === $alias ) {
			$i     = count( $this->table_aliases );
			$alias = $i ? 'mt' . $i : $this->meta_table;

			// JOIN clauses for NOT EXISTS have their own syntax.
			if ( 'NOT EXISTS' === $meta_compare ) {
				$join .= " LEFT JOIN $this->meta_table";
				$join .= $i ? " AS $alias" : '';

				if ( 'LIKE' === $meta_compare_key ) {
					$join .= $wpdb->prepare( " ON ( $this->primary_table.$this->primary_id_column = $alias.$this->meta_id_column AND $alias.meta_key LIKE %s )", '%' . $wpdb->esc_like( $clause['key'] ) . '%' );
				} else {
					$join .= $wpdb->prepare( " ON ( $this->primary_table.$this->primary_id_column = $alias.$this->meta_id_column AND $alias.meta_key = %s )", $clause['key'] );
				}

				// All other JOIN clauses.
			} else {
				$join .= " INNER JOIN $this->meta_table";
				$join .= $i ? " AS $alias" : '';
				$join .= " ON ( $this->primary_table.$this->primary_id_column = $alias.$this->meta_id_column )";
			}

			$this->table_aliases[] = $alias;
			$sql_chunks['join'][]  = $join;
		}

		// Save the alias to this clause, for future siblings to find.
		$clause['alias'] = $alias;

		// Determine the data type.
		$_meta_type     = isset( $clause['type'] ) ? $clause['type'] : '';
		$meta_type      = $this->get_cast_for_type( $_meta_type );
		$clause['cast'] = $meta_type;

		// Fallback for clause keys is the table alias. Key must be a string.
		if ( is_int( $clause_key ) || ! $clause_key ) {
			$clause_key = $clause['alias'];
		}

		// Ensure unique clause keys, so none are overwritten.
		$iterator        = 1;
		$clause_key_base = $clause_key;
		while ( isset( $this->clauses[ $clause_key ] ) ) {
			$clause_key = $clause_key_base . '-' . $iterator;
			++$iterator;
		}

		// Store the clause in our flat array.
		$this->clauses[ $clause_key ] =& $clause;

		// Next, build the WHERE clause.

		// meta_key.
		if ( array_key_exists( 'key', $clause ) ) {
			if ( 'NOT EXISTS' === $meta_compare ) {
				$sql_chunks['where'][] = $alias . '.' . $this->meta_id_column . ' IS NULL';
			} else {
				/**
				 * In joined clauses negative operators have to be nested into a
				 * NOT EXISTS clause and flipped, to avoid returning records with
				 * matching post IDs but different meta keys. Here we prepare the
				 * nested clause.
				 */
				if ( in_array( $meta_compare_key, array( '!=', 'NOT IN', 'NOT LIKE', 'NOT EXISTS', 'NOT REGEXP' ), true ) ) {
					// Negative clauses may be reused.
					$i                     = count( $this->table_aliases );
					$subquery_alias        = $i ? 'mt' . $i : $this->meta_table;
					$this->table_aliases[] = $subquery_alias;

					$meta_compare_string_start  = 'NOT EXISTS (';
					$meta_compare_string_start .= "SELECT 1 FROM $wpdb->postmeta $subquery_alias ";
					$meta_compare_string_start .= "WHERE $subquery_alias.post_ID = $alias.post_ID ";
					$meta_compare_string_end    = 'LIMIT 1';
					$meta_compare_string_end   .= ')';
				}

				switch ( $meta_compare_key ) {
					case '=':
					case 'EXISTS':
						$where = $wpdb->prepare( "$alias.meta_key = %s", trim( $clause['key'] ) ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
						break;
					case 'LIKE':
						$meta_compare_value = '%' . $wpdb->esc_like( trim( $clause['key'] ) ) . '%';
						$where              = $wpdb->prepare( "$alias.meta_key LIKE %s", $meta_compare_value ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
						break;
					case 'IN':
						$meta_compare_string = "$alias.meta_key IN (" . substr( str_repeat( ',%s', count( $clause['key'] ) ), 1 ) . ')';
						$where               = $wpdb->prepare( $meta_compare_string, $clause['key'] ); // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
						break;
					case 'RLIKE':
					case 'REGEXP':
						$operator = $meta_compare_key;
						if ( isset( $clause['type_key'] ) && 'BINARY' === strtoupper( $clause['type_key'] ) ) {
							$cast     = 'BINARY';
							$meta_key = "CAST($alias.meta_key AS BINARY)";
						} else {
							$cast     = '';
							$meta_key = "$alias.meta_key";
						}
						$where = $wpdb->prepare( "$meta_key $operator $cast %s", trim( $clause['key'] ) ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
						break;

					case '!=':
					case 'NOT EXISTS':
						$meta_compare_string = $meta_compare_string_start . "AND $subquery_alias.meta_key = %s " . $meta_compare_string_end;
						$where               = $wpdb->prepare( $meta_compare_string, $clause['key'] ); // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
						break;
					case 'NOT LIKE':
						$meta_compare_string = $meta_compare_string_start . "AND $subquery_alias.meta_key LIKE %s " . $meta_compare_string_end;

						$meta_compare_value = '%' . $wpdb->esc_like( trim( $clause['key'] ) ) . '%';
						$where              = $wpdb->prepare( $meta_compare_string, $meta_compare_value ); // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
						break;
					case 'NOT IN':
						$array_subclause     = '(' . substr( str_repeat( ',%s', count( $clause['key'] ) ), 1 ) . ') ';
						$meta_compare_string = $meta_compare_string_start . "AND $subquery_alias.meta_key IN " . $array_subclause . $meta_compare_string_end;
						$where               = $wpdb->prepare( $meta_compare_string, $clause['key'] ); // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
						break;
					case 'NOT REGEXP':
						$operator = $meta_compare_key;
						if ( isset( $clause['type_key'] ) && 'BINARY' === strtoupper( $clause['type_key'] ) ) {
							$cast     = 'BINARY';
							$meta_key = "CAST($subquery_alias.meta_key AS BINARY)";
						} else {
							$cast     = '';
							$meta_key = "$subquery_alias.meta_key";
						}

						$meta_compare_string = $meta_compare_string_start . "AND $meta_key REGEXP $cast %s " . $meta_compare_string_end;
						$where               = $wpdb->prepare( $meta_compare_string, $clause['key'] ); // phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared
						break;
				}

				$sql_chunks['where'][] = $where;
			}
		}

		// meta_value.
		if ( array_key_exists( 'value', $clause ) ) {
			$meta_value = $clause['value'];

			if ( in_array( $meta_compare, array( 'IN', 'NOT IN', 'BETWEEN', 'NOT BETWEEN' ), true ) ) {
				if ( ! is_array( $meta_value ) ) {
					$meta_value = preg_split( '/[,\s]+/', $meta_value );
				}
			} elseif ( is_string( $meta_value ) ) {
				$meta_value = trim( $meta_value );
			}

			switch ( $meta_compare ) {
				case 'IN':
				case 'NOT IN':
					$meta_compare_string = '(' . substr( str_repeat( ',%s', count( $meta_value ) ), 1 ) . ')';
					$where               = $wpdb->prepare( $meta_compare_string, $meta_value );
					break;

				case 'BETWEEN':
				case 'NOT BETWEEN':
					$where = $wpdb->prepare( '%s AND %s', $meta_value[0], $meta_value[1] );
					break;

				case 'LIKE':
				case 'NOT LIKE':
					$meta_value = '%' . $wpdb->esc_like( $meta_value ) . '%';
					$where      = $wpdb->prepare( '%s', $meta_value );
					break;

				// EXISTS with a value is interpreted as '='.
				case 'EXISTS':
					$meta_compare = '=';
					$where        = $wpdb->prepare( '%s', $meta_value );
					break;

				// 'value' is ignored for NOT EXISTS.
				case 'NOT EXISTS':
					$where = '';
					break;

				default:
					$where = $wpdb->prepare( '%s', $meta_value );
					break;

			}

			if ( $where ) {
				if ( 'CHAR' === $meta_type ) {
					$sql_chunks['where'][] = "$alias.meta_value {$meta_compare} {$where}";
				} else {
					$sql_chunks['where'][] = "CAST($alias.meta_value AS {$meta_type}) {$meta_compare} {$where}";
				}
			}
		}

		/*
		 * Multiple WHERE clauses (for meta_key and meta_value) should
		 * be joined in parentheses.
		 */
		if ( 1 < count( $sql_chunks['where'] ) ) {
			$sql_chunks['where'] = array( '( ' . implode( ' AND ', $sql_chunks['where'] ) . ' )' );
		}

		return $sql_chunks;
	}

	/**
	 * Gets a flattened list of sanitized meta clauses.
	 *
	 * This array should be used for clause lookup, as when the table alias and CAST type must be determined for
	 * a value of 'orderby' corresponding to a meta clause.
	 *
	 * @since 4.2.0
	 *
	 * @return array Meta clauses.
	 */
	public function get_clauses() {
		return $this->clauses;
	}

	/**
	 * Identifies an existing table alias that is compatible with the current
	 * query clause.
	 *
	 * We avoid unnecessary table joins by allowing each clause to look for
	 * an existing table alias that is compatible with the query that it
	 * needs to perform.
	 *
	 * An existing alias is compatible if (a) it is a sibling of `$clause`
	 * (ie, it's under the scope of the same relation), and (b) the combination
	 * of operator and relation between the clauses allows for a shared table join.
	 * In the case of WP_Meta_Query, this only applies to 'IN' clauses that are
	 * connected by the relation 'OR'.
	 *
	 * @since 4.1.0
	 *
	 * @param array $clause       Query clause.
	 * @param array $parent_query Parent query of $clause.
	 * @return string|false Table alias if found, otherwise false.
	 */
	protected function find_compatible_table_alias( $clause, $parent_query ) {
		$alias = false;

		foreach ( $parent_query as $sibling ) {
			// If the sibling has no alias yet, there's nothing to check.
			if ( empty( $sibling['alias'] ) ) {
				continue;
			}

			// We're only interested in siblings that are first-order clauses.
			if ( ! is_array( $sibling ) || ! $this->is_first_order_clause( $sibling ) ) {
				continue;
			}

			$compatible_compares = array();

			// Clauses connected by OR can share joins as long as they have "positive" operators.
			if ( 'OR' === $parent_query['relation'] ) {
				$compatible_compares = array( '=', 'IN', 'BETWEEN', 'LIKE', 'REGEXP', 'RLIKE', '>', '>=', '<', '<=' );

				// Clauses joined by AND with "negative" operators share a join only if they also share a key.
			} elseif ( isset( $sibling['key'] ) && isset( $clause['key'] ) && $sibling['key'] === $clause['key'] ) {
				$compatible_compares = array( '!=', 'NOT IN', 'NOT LIKE' );
			}

			$clause_compare  = strtoupper( $clause['compare'] );
			$sibling_compare = strtoupper( $sibling['compare'] );
			if ( in_array( $clause_compare, $compatible_compares, true ) && in_array( $sibling_compare, $compatible_compares, true ) ) {
				$alias = preg_replace( '/\W/', '_', $sibling['alias'] );
				break;
			}
		}

		/**
		 * Filters the table alias identified as compatible with the current clause.
		 *
		 * @since 4.1.0
		 *
		 * @param string|false  $alias        Table alias, or false if none was found.
		 * @param array         $clause       First-order query clause.
		 * @param array         $parent_query Parent of $clause.
		 * @param WP_Meta_Query $query        WP_Meta_Query object.
		 */
		return apply_filters( 'meta_query_find_compatible_table_alias', $alias, $clause, $parent_query, $this );
	}

	/**
	 * Checks whether the current query has any OR relations.
	 *
	 * In some cases, the presence of an OR relation somewhere in the query will require
	 * the use of a `DISTINCT` or `GROUP BY` keyword in the `SELECT` clause. The current
	 * method can be used in these cases to determine whether such a clause is necessary.
	 *
	 * @since 4.3.0
	 *
	 * @return bool True if the query contains any `OR` relations, otherwise false.
	 */
	public function has_or_relation() {
		return $this->has_or_relation;
	}
}
ta_update = $this->meta->update_value( $request['meta'], $term->term_id );

			if ( is_wp_error( $meta_update ) ) {
				return $meta_update;
			}
		}

		$fields_update = $this->update_additional_fields_for_object( $term, $request );

		if ( is_wp_error( $fields_update ) ) {
			return $fields_update;
		}

		$request->set_param( 'context', 'edit' );

		/** This action is documented in wp-includes/rest-api/endpoints/class-wp-rest-terms-controller.php */
		do_action( "rest_after_insert_{$this->taxonomy}", $term, $request, false );

		$response = $this->prepare_item_for_response( $term, $request );

		return rest_ensure_response( $response );
	}

	/**
	 * Checks if a request has access to delete the specified term.
	 *
	 * @since 4.7.0
	 *
	 * @param WP_REST_Request $request Full details about the request.
	 * @return true|WP_Error True if the request has access to delete the item, otherwise false or WP_Error object.
	 */
	public function delete_item_permissions_check( $request ) {
		$term = $this->get_term( $request['id'] );

		if ( is_wp_error( $term ) ) {
			return $term;
		}

		if ( ! current_user_can( 'delete_term', $term->term_id ) ) {
			return new WP_Error(
				'rest_cannot_delete',
				__( 'Sorry, you are not allowed to delete this term.' ),
				array( 'status' => rest_authorization_required_code() )
			);
		}

		return true;
	}

	/**
	 * Deletes a single term from a taxonomy.
	 *
	 * @since 4.7.0
	 *
	 * @param WP_REST_Request $request Full details about the request.
	 * @return WP_REST_Response|WP_Error Response object on success, or WP_Error object on failure.
	 */
	public function delete_item( $request ) {
		$term = $this->get_term( $request['id'] );
		if ( is_wp_error( $term ) ) {
			return $term;
		}

		$force = isset( $request['force'] ) ? (bool) $request['force'] : false;

		// We don't support trashing for terms.
		if ( ! $force ) {
			return new WP_Error(
				'rest_trash_not_supported',
				/* translators: %s: force=true */
				sprintf( __( "Terms do not support trashing. Set '%s' to delete." ), 'force=true' ),
				array( 'status' => 501 )
			);
		}

		$request->set_param( 'context', 'view' );

		$previous = $this->prepare_item_for_response( $term, $request );

		$retval = wp_delete_term( $term->term_id, $term->taxonomy );

		if ( ! $retval ) {
			return new WP_Error(
				'rest_cannot_delete',
				__( 'The term cannot be deleted.' ),
				array( 'status' => 500 )
			);
		}

		$response = new WP_REST_Response();
		$response->set_data(
			array(
				'deleted'  => true,
				'previous' => $previous->get_data(),
			)
		);

		/**
		 * Fires after a single term is deleted via the REST API.
		 *
		 * The dynamic portion of the hook name, `$this->taxonomy`, refers to the taxonomy slug.
		 *
		 * Possible hook names include:
		 *
		 *  - `rest_delete_category`
		 *  - `rest_delete_post_tag`
		 *
		 * @since 4.7.0
		 *
		 * @param WP_Term          $term     The deleted term.
		 * @param WP_REST_Response $response The response data.
		 * @param WP_REST_Request  $request  The request sent to the API.
		 */
		do_action( "rest_delete_{$this->taxonomy}", $term, $response, $request );

		return $response;
	}

	/**
	 * Prepares a single term for create or update.
	 *
	 * @since 4.7.0
	 *
	 * @param WP_REST_Request $request Request object.
	 * @return object Term object.
	 */
	public function prepare_item_for_database( $request ) {
		$prepared_term = new stdClass();

		$schema = $this->get_item_schema();
		if ( isset( $request['name'] ) && ! empty( $schema['properties']['name'] ) ) {
			$prepared_term->name = $request['name'];
		}

		if ( isset( $request['slug'] ) && ! empty( $schema['properties']['slug'] ) ) {
			$prepared_term->slug = $request['slug'];
		}

		if ( isset( $request['taxonomy'] ) && ! empty( $schema['properties']['taxonomy'] ) ) {
			$prepared_term->taxonomy = $request['taxonomy'];
		}

		if ( isset( $request['description'] ) && ! empty( $schema['properties']['description'] ) ) {
			$prepared_term->description = $request['description'];
		}

		if ( isset( $request['parent'] ) && ! empty( $schema['properties']['parent'] ) ) {
			$parent_term_id   = 0;
			$requested_parent = (int) $request['parent'];

			if ( $requested_parent ) {
				$parent_term = get_term( $requested_parent, $this->taxonomy );

				if ( $parent_term instanceof WP_Term ) {
					$parent_term_id = $parent_term->term_id;
				}
			}

			$prepared_term->parent = $parent_term_id;
		}

		/**
		 * Filters term data before inserting term via the REST API.
		 *
		 * The dynamic portion of the hook name, `$this->taxonomy`, refers to the taxonomy slug.
		 *
		 * Possible hook names include:
		 *
		 *  - `rest_pre_insert_category`
		 *  - `rest_pre_insert_post_tag`
		 *
		 * @since 4.7.0
		 *
		 * @param object          $prepared_term Term object.
		 * @param WP_REST_Request $request       Request object.
		 */
		return apply_filters( "rest_pre_insert_{$this->taxonomy}", $prepared_term, $request );
	}

	/**
	 * Prepares a single term output for response.
	 *
	 * @since 4.7.0
	 *
	 * @param WP_Term         $item    Term object.
	 * @param WP_REST_Request $request Request object.
	 * @return WP_REST_Response Response object.
	 */
	public function prepare_item_for_response( $item, $request ) {

		// Don't prepare the response body for HEAD requests.
		if ( $request->is_method( 'HEAD' ) ) {
			/** This filter is documented in wp-includes/rest-api/endpoints/class-wp-rest-terms-controller.php */
			return apply_filters( "rest_prepare_{$this->taxonomy}", new WP_REST_Response( array() ), $item, $request );
		}

		$fields = $this->get_fields_for_response( $request );
		$data   = array();

		if ( in_array( 'id', $fields, true ) ) {
			$data['id'] = (int) $item->term_id;
		}

		if ( in_array( 'count', $fields, true ) ) {
			$data['count'] = (int) $item->count;
		}

		if ( in_array( 'description', $fields, true ) ) {
			$data['description'] = $item->description;
		}

		if ( in_array( 'link', $fields, true ) ) {
			$data['link'] = get_term_link( $item );
		}

		if ( in_array( 'name', $fields, true ) ) {
			$data['name'] = $item->name;
		}

		if ( in_array( 'slug', $fields, true ) ) {
			$data['slug'] = $item->slug;
		}

		if ( in_array( 'taxonomy', $fields, true ) ) {
			$data['taxonomy'] = $item->taxonomy;
		}

		if ( in_array( 'parent', $fields, true ) ) {
			$data['parent'] = (int) $item->parent;
		}

		if ( in_array( 'meta', $fields, true ) ) {
			$data['meta'] = $this->meta->get_value( $item->term_id, $request );
		}

		$context = ! empty( $request['context'] ) ? $request['context'] : 'view';
		$data    = $this->add_additional_fields_to_object( $data, $request );
		$data    = $this->filter_response_by_context( $data, $context );

		$response = rest_ensure_response( $data );

		if ( rest_is_field_included( '_links', $fields ) || rest_is_field_included( '_embedded', $fields ) ) {
			$response->add_links( $this->prepare_links( $item ) );
		}

		/**
		 * Filters the term data for a REST API response.
		 *
		 * The dynamic portion of the hook name, `$this->taxonomy`, refers to the taxonomy slug.
		 *
		 * Possible hook names include:
		 *
		 *  - `rest_prepare_category`
		 *  - `rest_prepare_post_tag`
		 *
		 * Allows modification of the term data right before it is returned.
		 *
		 * @since 4.7.0
		 *
		 * @param WP_REST_Response  $response  The response object.
		 * @param WP_Term           $item      The original term object.
		 * @param WP_REST_Request   $request   Request used to generate the response.
		 */
		return apply_filters( "rest_prepare_{$this->taxonomy}", $response, $item, $request );
	}

	/**
	 * Prepares links for the request.
	 *
	 * @since 4.7.0
	 *
	 * @param WP_Term $term Term object.
	 * @return array Links for the given term.
	 */
	protected function prepare_links( $term ) {
		$links = array(
			'self'       => array(
				'href' => rest_url( rest_get_route_for_term( $term ) ),
			),
			'collection' => array(
				'href' => rest_url( rest_get_route_for_taxonomy_items( $this->taxonomy ) ),
			),
			'about'      => array(
				'href' => rest_url( sprintf( 'wp/v2/taxonomies/%s', $this->taxonomy ) ),
			),
		);

		if ( $term->parent ) {
			$parent_term = get_term( (int) $term->parent, $term->taxonomy );

			if ( $parent_term ) {
				$links['up'] = array(
					'href'       => rest_url( rest_get_route_for_term( $parent_term ) ),
					'embeddable' => true,
				);
			}
		}

		$taxonomy_obj = get_taxonomy( $term->taxonomy );

		if ( empty( $taxonomy_obj->object_type ) ) {
			return $links;
		}

		$post_type_links = array();

		foreach ( $taxonomy_obj->object_type as $type ) {
			$rest_path = rest_get_route_for_post_type_items( $type );

			if ( empty( $rest_path ) ) {
				continue;
			}

			$post_type_links[] = array(
				'href' => add_query_arg( $this->rest_base, $term->term_id, rest_url( $rest_path ) ),
			);
		}

		if ( ! empty( $post_type_links ) ) {
			$links['https://api.w.org/post_type'] = $post_type_links;
		}

		return $links;
	}

	/**
	 * Retrieves the term's schema, conforming to JSON Schema.
	 *
	 * @since 4.7.0
	 *
	 * @return array Item schema data.
	 */
	public function get_item_schema() {
		if ( $this->schema ) {
			return $this->add_additional_fields_schema( $this->schema );
		}

		$schema = array(
			'$schema'    => 'http://json-schema.org/draft-04/schema#',
			'title'      => 'post_tag' === $this->taxonomy ? 'tag' : $this->taxonomy,
			'type'       => 'object',
			'properties' => array(
				'id'          => array(
					'description' => __( 'Unique identifier for the term.' ),
					'type'        => 'integer',
					'context'     => array( 'view', 'embed', 'edit' ),
					'readonly'    => true,
				),
				'count'       => array(
					'description' => __( 'Number of published posts for the term.' ),
					'type'        => 'integer',
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
				),
				'description' => array(
					'description' => __( 'HTML description of the term.' ),
					'type'        => 'string',
					'context'     => array( 'view', 'edit' ),
				),
				'link'        => array(
					'description' => __( 'URL of the term.' ),
					'type'        => 'string',
					'format'      => 'uri',
					'context'     => array( 'view', 'embed', 'edit' ),
					'readonly'    => true,
				),
				'name'        => array(
					'description' => __( 'HTML title for the term.' ),
					'type'        => 'string',
					'context'     => array( 'view', 'embed', 'edit' ),
					'arg_options' => array(
						'sanitize_callback' => 'sanitize_text_field',
					),
					'required'    => true,
				),
				'slug'        => array(
					'description' => __( 'An alphanumeric identifier for the term unique to its type.' ),
					'type'        => 'string',
					'context'     => array( 'view', 'embed', 'edit' ),
					'arg_options' => array(
						'sanitize_callback' => array( $this, 'sanitize_slug' ),
					),
				),
				'taxonomy'    => array(
					'description' => __( 'Type attribution for the term.' ),
					'type'        => 'string',
					'enum'        => array( $this->taxonomy ),
					'context'     => array( 'view', 'embed', 'edit' ),
					'readonly'    => true,
				),
			),
		);

		$taxonomy = get_taxonomy( $this->taxonomy );

		if ( $taxonomy->hierarchical ) {
			$schema['properties']['parent'] = array(
				'description' => __( 'The parent term ID.' ),
				'type'        => 'integer',
				'context'     => array( 'view', 'edit' ),
			);
		}

		$schema['properties']['meta'] = $this->meta->get_field_schema();

		$this->schema = $schema;

		return $this->add_additional_fields_schema( $this->schema );
	}

	/**
	 * Retrieves the query params for collections.
	 *
	 * @since 4.7.0
	 *
	 * @return array Collection parameters.
	 */
	public function get_collection_params() {
		$query_params = parent::get_collection_params();
		$taxonomy     = get_taxonomy( $this->taxonomy );

		$query_params['context']['default'] = 'view';

		$query_params['exclude'] = array(
			'description' => __( 'Ensure result set excludes specific IDs.' ),
			'type'        => 'array',
			'items'       => array(
				'type' => 'integer',
			),
			'default'     => array(),
		);

		$query_params['include'] = array(
			'description' => __( 'Limit result set to specific IDs.' ),
			'type'        => 'array',
			'items'       => array(
				'type' => 'integer',
			),
			'default'     => array(),
		);

		if ( ! $taxonomy->hierarchical ) {
			$query_params['offset'] = array(
				'description' => __( 'Offset the result set by a specific number of items.' ),
				'type'        => 'integer',
			);
		}

		$query_params['order'] = array(
			'description' => __( 'Order sort attribute ascending or descending.' ),
			'type'        => 'string',
			'default'     => 'asc',
			'enum'        => array(
				'asc',
				'desc',
			),
		);

		$query_params['orderby'] = array(
			'description' => __( 'Sort collection by term attribute.' ),
			'type'        => 'string',
			'default'     => 'name',
			'enum'        => array(
				'id',
				'include',
				'name',
				'slug',
				'include_slugs',
				'term_group',
				'description',
				'count',
			),
		);

		$query_params['hide_empty'] = array(
			'description' => __( 'Whether to hide terms not assigned to any posts.' ),
			'type'        => 'boolean',
			'default'     => false,
		);

		if ( $taxonomy->hierarchical ) {
			$query_params['parent'] = array(
				'description' => __( 'Limit result set to terms assigned to a specific parent.' ),
				'type'        => 'integer',
			);
		}

		$query_params['post'] = array(
			'description' => __( 'Limit result set to terms assigned to a specific post.' ),
			'type'        => 'integer',
			'default'     => null,
		);

		$query_params['slug'] = array(
			'description' => __( 'Limit result set to terms with one or more specific slugs.' ),
			'type'        => 'array',
			'items'       => array(
				'type' => 'string',
			),
		);

		/**
		 * Filters collection parameters for the terms controller.
		 *
		 * The dynamic part of the filter `$this->taxonomy` refers to the taxonomy
		 * slug for the controller.
		 *
		 * This filter registers the collection parameter, but does not map the
		 * collection parameter to an internal WP_Term_Query parameter.  Use the
		 * `rest_{$this->taxonomy}_query` filter to set WP_Term_Query parameters.
		 *
		 * @since 4.7.0
		 *
		 * @param array       $query_params JSON Schema-formatted collection parameters.
		 * @param WP_Taxonomy $taxonomy     Taxonomy object.
		 */
		return apply_filters( "rest_{$this->taxonomy}_collection_params", $query_params, $taxonomy );
	}

	/**
	 * Checks that the taxonomy is valid.
	 *
	 * @since 4.7.0
	 *
	 * @param string $taxonomy Taxonomy to check.
	 * @return bool Whether the taxonomy is allowed for REST management.
	 */
	protected function check_is_taxonomy_allowed( $taxonomy ) {
		$taxonomy_obj = get_taxonomy( $taxonomy );
		if ( $taxonomy_obj && ! empty( $taxonomy_obj->show_in_rest ) ) {
			return true;
		}
		return false;
	}
}