Retrieves the character set for the given table.
Parameters
$table
stringrequired- Table name.
Source
protected function get_table_charset( $table ) {
$tablekey = strtolower( $table );
/**
* Filters the table charset value before the DB is checked.
*
* Returning a non-null value from the filter will effectively short-circuit
* checking the DB for the charset, returning that value instead.
*
* @since 4.2.0
*
* @param string|WP_Error|null $charset The character set to use, WP_Error object
* if it couldn't be found. Default null.
* @param string $table The name of the table being checked.
*/
$charset = apply_filters( 'pre_get_table_charset', null, $table );
if ( null !== $charset ) {
return $charset;
}
if ( isset( $this->table_charset[ $tablekey ] ) ) {
return $this->table_charset[ $tablekey ];
}
$charsets = array();
$columns = array();
$table_parts = explode( '.', $table );
$table = '`' . implode( '`.`', $table_parts ) . '`';
$results = $this->get_results( "SHOW FULL COLUMNS FROM $table" );
if ( ! $results ) {
return new WP_Error( 'wpdb_get_table_charset_failure', __( 'Could not retrieve table charset.' ) );
}
foreach ( $results as $column ) {
$columns[ strtolower( $column->Field ) ] = $column;
}
$this->col_meta[ $tablekey ] = $columns;
foreach ( $columns as $column ) {
if ( ! empty( $column->Collation ) ) {
list( $charset ) = explode( '_', $column->Collation );
$charsets[ strtolower( $charset ) ] = true;
}
list( $type ) = explode( '(', $column->Type );
// A binary/blob means the whole query gets treated like this.
if ( in_array( strtoupper( $type ), array( 'BINARY', 'VARBINARY', 'TINYBLOB', 'MEDIUMBLOB', 'BLOB', 'LONGBLOB' ), true ) ) {
$this->table_charset[ $tablekey ] = 'binary';
return 'binary';
}
}
// utf8mb3 is an alias for utf8.
if ( isset( $charsets['utf8mb3'] ) ) {
$charsets['utf8'] = true;
unset( $charsets['utf8mb3'] );
}
// Check if we have more than one charset in play.
$count = count( $charsets );
if ( 1 === $count ) {
$charset = key( $charsets );
} elseif ( 0 === $count ) {
// No charsets, assume this table can store whatever.
$charset = false;
} else {
// More than one charset. Remove latin1 if present and recalculate.
unset( $charsets['latin1'] );
$count = count( $charsets );
if ( 1 === $count ) {
// Only one charset (besides latin1).
$charset = key( $charsets );
} elseif ( 2 === $count && isset( $charsets['utf8'], $charsets['utf8mb4'] ) ) {
// Two charsets, but they're utf8 and utf8mb4, use utf8.
$charset = 'utf8';
} else {
// Two mixed character sets. ascii.
$charset = 'ascii';
}
}
$this->table_charset[ $tablekey ] = $charset;
return $charset;
}
Hooks
- apply_filters( ‘pre_get_table_charset’,
string|WP_Error|null $charset ,string $table ) Filters the table charset value before the DB is checked.
Changelog
Version | Description |
---|---|
4.2.0 | Introduced. |
User Contributed Notes
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