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Fix get_col_charset and get_col_length when using pre_get_table_charset filter #10646

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Fix get_col_charset and get_col_length when using pre_get_table_charset filter #10646

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cb73ba7
Failing test for ticket 38921
matt-h Dec 17, 2025
f45fe86
Change how column meta is pulled so it uses a get_cols_meta function
matt-h Dec 17, 2025
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175 changes: 124 additions & 51 deletions src/wp-includes/class-wpdb.php
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Original file line number Diff line number Diff line change
Expand Up @@ -3227,21 +3227,15 @@ protected function get_table_charset( $table ) {
}

$charsets = array();
$columns = array();
$columns = $this->get_cols_meta( $table );
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@mukeshpanchal27 mukeshpanchal27 Dec 20, 2025

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Use $tablekey as it convert $table value to strtolower and remove strtolower from get_cols_meta.

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@matt-h matt-h Dec 20, 2025

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I don't agree with this. Using $tablekey would be fine here, but strtolower shouldn't be removed from get_cols_meta as get_cols_meta is used in more than 1 place and could be used elsewhere in the future. Removing it from there would require a tablekey being passed in all the time instead of just table so you'd always need to make sure strtolower is called first which would make the function less resilient/consistant.


$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.' ) );
if ( is_wp_error( $columns ) ) {
return $columns;
}

foreach ( $results as $column ) {
$columns[ strtolower( $column->Field ) ] = $column;
if ( empty( $columns ) ) {
$columns = array();
}

$this->col_meta[ $tablekey ] = $columns;

foreach ( $columns as $column ) {
if ( ! empty( $column->Collation ) ) {
list( $charset ) = explode( '_', $column->Collation );
Expand Down Expand Up @@ -3291,6 +3285,109 @@ protected function get_table_charset( $table ) {
return $charset;
}

/**
* Retrieves the column metadata for the given column.
*
* @since 7.0.0
*
* @param string $table Table name.
* @return object|false|WP_Error Column meta set as an object. False if the column was
* not found. WP_Error object if there was an error.
*/
public function get_cols_meta( $table ) {
$tablekey = strtolower( $table );

/**
* Filters the columns meta value before the DB is checked.
*
* Passing a non-null value to the filter will short-circuit
* checking the DB for the meta, returning that value instead.
*
* @since 7.0.0
*
* @param object[]|null|false|WP_Error $meta The meta to use. Default null.
* @param string $table The name of the table being checked.
*/
$col_meta = apply_filters( 'pre_get_cols_meta', null, $table );
if ( null !== $col_meta ) {
return $col_meta;
}

// Skip this entirely if this isn't a MySQL database.
if ( empty( $this->is_mysql ) ) {
return false;
}

// If no column information, fetch it from the database.
if ( empty( $this->col_meta[ $tablekey ] ) ) {
$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_cols_meta_failure', __( 'Could not retrieve column metadata.' ) );
}

foreach ( $results as $column ) {
$columns[ strtolower( $column->Field ) ] = $column;
}

$this->col_meta[ $tablekey ] = $columns;
}

// If this table data doesn't exist, return false.
if ( empty( $this->col_meta[ $tablekey ] ) ) {
return false;
}

return $this->col_meta[ $tablekey ];
}

/**
* Retrieves the column metadata for the given column.
*
* @since 7.0.0
*
* @param string $table Table name.
* @param string $column Column name.
* @return object|false|WP_Error Column character set as a string. False if the column has
* no character set. WP_Error object if there was an error.
*/
public function get_col_meta( $table, $column ) {
$columnkey = strtolower( $column );

/**
* Filters the column meta value before the DB is checked.
*
* Passing a non-null value to the filter will short-circuit
* checking the DB for the meta, returning that value instead.
*
* @since 7.0.0
*
* @param object|null|false|WP_Error $meta The meta to use. Default null.
* @param string $table The name of the table being checked.
* @param string $column The name of the column being checked.
*/
$col_meta = apply_filters( 'pre_get_col_meta', null, $table, $column );
if ( null !== $col_meta ) {
return $col_meta;
}

$cols_meta = $this->get_cols_meta( $table );

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

// If this column doesn't exist, return false.
if ( empty( $cols_meta[ $columnkey ] ) ) {
return false;
}

return $cols_meta[ $columnkey ];
}

/**
* Retrieves the character set for the given column.
*
Expand All @@ -3302,9 +3399,6 @@ protected function get_table_charset( $table ) {
* no character set. WP_Error object if there was an error.
*/
public function get_col_charset( $table, $column ) {
$tablekey = strtolower( $table );
$columnkey = strtolower( $column );

/**
* Filters the column charset value before the DB is checked.
*
Expand All @@ -3322,35 +3416,23 @@ public function get_col_charset( $table, $column ) {
return $charset;
}

// Skip this entirely if this isn't a MySQL database.
if ( empty( $this->is_mysql ) ) {
return false;
}

if ( empty( $this->table_charset[ $tablekey ] ) ) {
// This primes column information for us.
$table_charset = $this->get_table_charset( $table );
if ( is_wp_error( $table_charset ) ) {
return $table_charset;
}
}
$col_meta = $this->get_col_meta( $table, $column );

// If still no column information, return the table charset.
if ( empty( $this->col_meta[ $tablekey ] ) ) {
return $this->table_charset[ $tablekey ];
if ( is_wp_error( $col_meta ) ) {
return $col_meta;
}

// If this column doesn't exist, return the table charset.
if ( empty( $this->col_meta[ $tablekey ][ $columnkey ] ) ) {
return $this->table_charset[ $tablekey ];
if ( empty( $col_meta ) ) {
return $this->get_table_charset( $table );
}

// Return false when it's not a string column.
if ( empty( $this->col_meta[ $tablekey ][ $columnkey ]->Collation ) ) {
if ( empty( $col_meta->Collation ) ) {
return false;
}

list( $charset ) = explode( '_', $this->col_meta[ $tablekey ][ $columnkey ]->Collation );
list( $charset ) = explode( '_', $col_meta->Collation );
return $charset;
}

Expand All @@ -3372,27 +3454,17 @@ public function get_col_charset( $table, $column ) {
* }
*/
public function get_col_length( $table, $column ) {
$tablekey = strtolower( $table );
$columnkey = strtolower( $column );

// Skip this entirely if this isn't a MySQL database.
if ( empty( $this->is_mysql ) ) {
return false;
}
$col_meta = $this->get_col_meta( $table, $column );

if ( empty( $this->col_meta[ $tablekey ] ) ) {
// This primes column information for us.
$table_charset = $this->get_table_charset( $table );
if ( is_wp_error( $table_charset ) ) {
return $table_charset;
}
if ( is_wp_error( $col_meta ) ) {
return $col_meta;
}

if ( empty( $this->col_meta[ $tablekey ][ $columnkey ] ) ) {
if ( empty( $col_meta ) ) {
return false;
}

$typeinfo = explode( '(', $this->col_meta[ $tablekey ][ $columnkey ]->Type );
$typeinfo = explode( '(', $col_meta->Type );

$type = strtolower( $typeinfo[0] );
if ( ! empty( $typeinfo[1] ) ) {
Expand Down Expand Up @@ -3510,8 +3582,9 @@ protected function check_safe_collation( $query ) {
return true;
}

$table = strtolower( $table );
if ( empty( $this->col_meta[ $table ] ) ) {
$cols_meta = $this->get_cols_meta( $table );

if ( is_wp_error( $cols_meta ) || empty( $cols_meta ) ) {
return false;
}

Expand All @@ -3525,7 +3598,7 @@ protected function check_safe_collation( $query ) {
'utf8mb4_general_ci',
);

foreach ( $this->col_meta[ $table ] as $col ) {
foreach ( $cols_meta as $col ) {
if ( empty( $col->Collation ) ) {
continue;
}
Expand Down
5 changes: 5 additions & 0 deletions tests/phpunit/includes/utils.php
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Original file line number Diff line number Diff line change
Expand Up @@ -571,6 +571,11 @@ public function __construct() {
public function __call( $name, $arguments ) {
return call_user_func_array( array( $this, $name ), $arguments );
}

public function reset_cache_values() {
$this->table_charset = array();
$this->col_meta = array();
}
}

/**
Expand Down
31 changes: 31 additions & 0 deletions tests/phpunit/tests/db.php
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Original file line number Diff line number Diff line change
Expand Up @@ -2486,4 +2486,35 @@ public function test_check_connection_returns_true_when_there_is_a_connection()

$this->assertTrue( $wpdb->check_connection( false ) );
}

/**
* Tests if the column charset doesn't throw errors with the `pre_get_table_charset` filter.
*
* @ticket 38921
*/
public function test_get_table_and_column_charset_with_pre_get_table_charset_filter() {
global $wpdb;
$expected_charset = $wpdb->get_col_charset( $wpdb->posts, 'post_content' );

self::$_wpdb->reset_cache_values();

add_filter( 'pre_get_table_charset', array( $this, 'change_table_charset_callback' ), 10, 2 );
$table_charset = self::$_wpdb->get_table_charset( $wpdb->posts );
$column_charset = self::$_wpdb->get_col_charset( $wpdb->posts, 'post_content' );
remove_filter( 'pre_get_table_charset', array( $this, 'change_table_charset_callback' ), 10, 2 );

$this->assertSame( 'fake_charset', $table_charset );
$this->assertSame( $expected_charset, $column_charset );
}

/**
* Callback for the `pre_get_table_charset` filter.
*
* @param string $charset The table's character set.
* @param string $table The name of the table.
* @return string $charset The table's character set.
*/
public function change_table_charset_callback( $charset, $table ) {
return 'fake_charset';
}
}
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