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wpdb::determine_charset( string $charset, string $collate )

Determines the best charset and collation to use given a charset and collation.

Description

For example, when able, utf8mb4 should be used instead of utf8.

Parameters

$charset

(string) (Required) The character set to check.

$collate

(string) (Required) The collation to check.

Return

(array) The most appropriate character set and collation to use.

  • 'charset'
    (string) Character set.
  • 'collate'
    (string) Collation.

Source

File: wp-includes/wp-db.php

public function determine_charset( $charset, $collate ) {
		if ( ( $this->use_mysqli && ! ( $this->dbh instanceof mysqli ) ) || empty( $this->dbh ) ) {
			return compact( 'charset', 'collate' );
		}

		if ( 'utf8' === $charset && $this->has_cap( 'utf8mb4' ) ) {
			$charset = 'utf8mb4';
		}

		if ( 'utf8mb4' === $charset && ! $this->has_cap( 'utf8mb4' ) ) {
			$charset = 'utf8';
			$collate = str_replace( 'utf8mb4_', 'utf8_', $collate );
		}

		if ( 'utf8mb4' === $charset ) {
			// _general_ is outdated, so we can upgrade it to _unicode_, instead.
			if ( ! $collate || 'utf8_general_ci' === $collate ) {
				$collate = 'utf8mb4_unicode_ci';
			} else {
				$collate = str_replace( 'utf8_', 'utf8mb4_', $collate );
			}
		}

		// _unicode_520_ is a better collation, we should use that when it's available.
		if ( $this->has_cap( 'utf8mb4_520' ) && 'utf8mb4_unicode_ci' === $collate ) {
			$collate = 'utf8mb4_unicode_520_ci';
		}

		return compact( 'charset', 'collate' );
	}

Changelog

Version Description
4.6.0 Introduced.

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