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

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

$charsetstringrequired
The character set to check.
$collatestringrequired
The collation to check.

Return

array The most appropriate character set and collation to use.
  • charset string
    Character set.
  • collate string
    Collation.

Source

public function determine_charset( $charset, $collate ) {
	if ( ( ! ( $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		// _general_ is outdated, so we can upgrade it to _unicode_, instead.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

VersionDescription
4.6.0Introduced.

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