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Add support for ALTER COLUMN with SET DEFAULT and DROP DEFAULT
#555
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−16
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -765,6 +765,16 @@ public function record_alter_table( WP_Parser_Node $node ): void { | |
| continue; | ||
| } | ||
| } | ||
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| // ALTER [COLUMN] | ||
| if ( WP_MySQL_Lexer::ALTER_SYMBOL === $first_token->id ) { | ||
| // SET DEFAULT and DROP DEFAULT | ||
| $column_ref = $action->get_first_child_node( 'fieldIdentifier' ); | ||
| if ( null !== $column_ref && $action->has_child_token( WP_MySQL_Lexer::DEFAULT_SYMBOL ) ) { | ||
| $name = $this->get_value( $column_ref ); | ||
| $this->record_alter_column_default( $table_is_temporary, $table_name, $name, $action ); | ||
| } | ||
| } | ||
| } | ||
| } | ||
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@@ -1002,6 +1012,103 @@ private function record_modify_column( | |
| $this->record_change_column( $table_is_temporary, $table_name, $column_name, $column_name, $node ); | ||
| } | ||
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| /** | ||
| * Record SET DEFAULT or DROP DEFAULT data in the information schema. | ||
| * | ||
| * @param bool $table_is_temporary Whether the table is temporary. | ||
| * @param string $table_name The table name. | ||
| * @param string $column_name The column name. | ||
| * @param WP_Parser_Node $node The "alterListItem" AST node. | ||
| */ | ||
| private function record_alter_column_default( | ||
| bool $table_is_temporary, | ||
| string $table_name, | ||
| string $column_name, | ||
| WP_Parser_Node $node | ||
| ): void { | ||
| $columns_table = $this->get_table_name( $table_is_temporary, 'columns' ); | ||
| $column = $this->connection->query( | ||
| 'SELECT DATA_TYPE, IS_NULLABLE, EXTRA FROM ' . $this->connection->quote_identifier( $columns_table ) . ' | ||
| WHERE table_schema = ? AND table_name = ? AND column_name = ?', | ||
| array( self::SAVED_DATABASE_NAME, $table_name, $column_name ) | ||
| )->fetch( PDO::FETCH_ASSOC ); | ||
| if ( false === $column ) { | ||
| throw WP_SQLite_Information_Schema_Exception::column_not_found( $column_name, $table_name ); | ||
| } | ||
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| /* | ||
| * MySQL accepts these changes but hides them from its schema. | ||
| * These are known MySQL bugs that are not worth replicating. | ||
| * | ||
| * @see https://bugs.mysql.com/bug.php?id=111702 | ||
| * @see https://bugs.mysql.com/bug.php?id=80222 | ||
| */ | ||
| if ( str_contains( $column['EXTRA'], 'auto_increment' ) ) { | ||
| throw new Exception( 'SET DEFAULT and DROP DEFAULT on AUTO_INCREMENT columns are not supported.' ); | ||
| } | ||
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| $default = null; | ||
| $extra = trim( str_replace( 'DEFAULT_GENERATED', '', $column['EXTRA'] ) ); | ||
| if ( $node->has_child_token( WP_MySQL_Lexer::SET_SYMBOL ) ) { | ||
| $expression = $node->get_first_child_node( 'exprWithParentheses' ); | ||
| $literal = $expression ? $this->get_parenthesized_default_literal( $expression ) : null; | ||
| $default = $literal | ||
| ? $this->get_literal_default( $literal, $column['DATA_TYPE'], $column_name ) | ||
| : $this->get_default_value( $node, $column['DATA_TYPE'], $column_name ); | ||
| if ( null === $default && 'NO' === $column['IS_NULLABLE'] ) { | ||
| throw WP_SQLite_Information_Schema_Exception::invalid_default_value( $column_name ); | ||
| } | ||
| if ( $expression && ! $literal ) { | ||
| $extra = trim( 'DEFAULT_GENERATED ' . $extra ); | ||
|
Member
There was a problem hiding this comment. Codex review feedback, requested by @brandonpayton. Expression defaults can disable Suggested fix: Use
Member
Author
There was a problem hiding this comment. Thanks, I found this during self-review but decided to extract it to #554. The reason is that doing only the |
||
| } | ||
| } | ||
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| $this->update_values( | ||
| $columns_table, | ||
| array( | ||
| 'column_default' => $default, | ||
| 'extra' => $extra, | ||
| ), | ||
| array( | ||
| 'table_schema' => self::SAVED_DATABASE_NAME, | ||
| 'table_name' => $table_name, | ||
| 'column_name' => $column_name, | ||
| ) | ||
| ); | ||
| } | ||
|
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| /** | ||
| * Find a literal wrapped only in parentheses or unary plus operators. | ||
| * | ||
| * @param WP_Parser_Node $node The default expression. | ||
| * @return WP_Parser_Node|null The literal, or null for other expressions. | ||
| */ | ||
| private function get_parenthesized_default_literal( WP_Parser_Node $node ): ?WP_Parser_Node { | ||
| while ( 'literal' !== $node->rule_name ) { | ||
| $children = $node->get_children(); | ||
| if ( | ||
| 3 === count( $children ) | ||
| && $children[0] instanceof WP_Parser_Token | ||
| && WP_MySQL_Lexer::OPEN_PAR_SYMBOL === $children[0]->id | ||
| && $children[2] instanceof WP_Parser_Token | ||
| && WP_MySQL_Lexer::CLOSE_PAR_SYMBOL === $children[2]->id | ||
| ) { | ||
| $children = array( $children[1] ); | ||
| } elseif ( | ||
| 2 === count( $children ) | ||
| && $children[0] instanceof WP_Parser_Token | ||
| && WP_MySQL_Lexer::PLUS_OPERATOR === $children[0]->id | ||
| ) { | ||
| $children = array( $children[1] ); | ||
| } | ||
| if ( 1 !== count( $children ) || ! $children[0] instanceof WP_Parser_Node ) { | ||
| return null; | ||
| } | ||
| $node = $children[0]; | ||
| } | ||
| return $node; | ||
| } | ||
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| /** | ||
| * Record DROP COLUMN data in the information schema. | ||
| * | ||
|
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@@ -2079,34 +2186,54 @@ private function get_column_default( WP_Parser_Node $node, string $data_type, st | |
| if ( null === $default_attr ) { | ||
| return null; | ||
| } | ||
| return $this->get_default_value( $default_attr, $data_type, $column_name ); | ||
| } | ||
|
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| /** | ||
| * Extract a default value from a column attribute or ALTER COLUMN action. | ||
| * | ||
| * @param WP_Parser_Node $node The "columnAttribute" or "alterListItem" AST node. | ||
| * @param string $data_type The column data type as stored in information schema. | ||
| * @param string $column_name The column name. | ||
| * @return string|null The default value as stored in information schema. | ||
| */ | ||
| private function get_default_value( WP_Parser_Node $node, string $data_type, string $column_name ): ?string { | ||
| /* | ||
| * [GRAMMAR] | ||
| * columnAttribute: | ||
| * DEFAULT_SYMBOL ( | ||
| * signedLiteral | ||
| * | NOW_SYMBOL timeFunctionParameters? | ||
| * | {serverVersion >= 80013}? exprWithParentheses | ||
| * ) | ||
| * | ||
| * alterListItem: | ||
| * ALTER_SYMBOL COLUMN_SYMBOL? fieldIdentifier SET_SYMBOL DEFAULT_SYMBOL ( | ||
| * {serverVersion >= 80014}? exprWithParentheses | ||
| * | signedLiteral | ||
| * ) | ||
| */ | ||
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| // DEFAULT NOW() | ||
| if ( $node->has_child_token( WP_MySQL_Lexer::NOW_SYMBOL ) ) { | ||
| return 'CURRENT_TIMESTAMP'; | ||
| } | ||
|
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| // DEFAULT signedLiteral | ||
| $signed_literal = $node->get_first_child_node( 'signedLiteral' ); | ||
| if ( $signed_literal ) { | ||
| $literal = $signed_literal->get_first_child_node( 'literal' ); | ||
| if ( null === $literal ) { | ||
| // A signed number, such as "-5", has no "literal" child node. | ||
| // Like MySQL, drop the unary plus, e.g., "+5" becomes "5". | ||
| $number = ltrim( $this->get_value( $signed_literal ), '+' ); | ||
| return $this->normalize_literal_default( $number, $data_type, $column_name ); | ||
| } | ||
| return $this->get_literal_default( $literal, $data_type, $column_name ); | ||
| } | ||
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| // DEFAULT (expression) - MySQL 8.0.13+ supports exprWithParentheses | ||
| $expr_with_parens = $node->get_first_child_node( 'exprWithParentheses' ); | ||
| if ( $expr_with_parens ) { | ||
| return $this->serialize_mysql_expression( $expr_with_parens ); | ||
| } | ||
|
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@@ -2135,14 +2262,24 @@ private function get_literal_default( WP_Parser_Node $literal, string $data_type | |
| return 'bit' === $data_type ? "b'{$bool_value}'" : $bool_value; | ||
| } | ||
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| return $this->normalize_literal_default( $this->get_value( $literal ), $data_type, $column_name ); | ||
| } | ||
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| /** | ||
| * Normalize a literal default value for the column data type. | ||
| * | ||
| * @param string $default_value The literal default value. | ||
| * @param string $data_type The column data type as stored in information schema. | ||
| * @param string $column_name The column name. | ||
| * @return string The default value as stored in information schema. | ||
| */ | ||
| private function normalize_literal_default( string $default_value, string $data_type, string $column_name ): string { | ||
| if ( 'bit' === $data_type ) { | ||
| /* | ||
| * @TODO: Validate and normalize defaults from their AST and the full | ||
| * column definition before storing them in the information schema. | ||
| */ | ||
| $bit_default = $this->get_bit_default( $default_value ); | ||
| if ( null === $bit_default ) { | ||
| throw WP_SQLite_Information_Schema_Exception::invalid_default_value( $column_name ); | ||
| } | ||
|
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@@ -2158,13 +2295,13 @@ private function get_literal_default( WP_Parser_Node $literal, string $data_type | |
| * - The charset introducer dropped from text-literal defaults. | ||
| * - Numeric defaults normalized, e.g. 1.0 to 1 or 1e3 to 1000. | ||
| */ | ||
| return $default_value; | ||
| } | ||
|
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| /** | ||
| * Normalize a BIT default value to a MySQL bit literal. | ||
| * | ||
| * The value may be a bit literal, a hex literal, or a non-negative decimal. | ||
| * | ||
| * @param string $default_value The BIT default value. | ||
| * @return string|null The default as a bit literal, e.g. "b'101'", or null when not a bit value. | ||
|
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@@ -2194,8 +2331,8 @@ private function get_bit_default( string $default_value ): ?string { | |
| return "b'" . decbin( hexdec( $matches[1] ) ) . "'"; | ||
| } | ||
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| // Non-negative decimal, e.g. 5, or a numeric string literal such as '0'. | ||
| if ( is_numeric( $value ) && $value >= 0 ) { | ||
| return "b'" . decbin( (int) $value ) . "'"; | ||
| } | ||
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Codex review feedback, requested by @brandonpayton.
Invalid literal defaults can be accepted and break later inserts. For example,
SET DEFAULT 'invalid'succeeds on anINTcolumn, then inserts omitting that column fail. This is an existing validation gap exposed by the new ALTER support.Suggested fix: Add shared validation and normalization using the literal AST and complete column metadata. Reuse it across CREATE and ALTER operations, raise the existing invalid-default exception, and test rollback. This broader work could be a separate follow-up.
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Agreed. This is fairly complex because it requires extensive type conversion and validation in PHP. It’s already tracked in #551 (and pre-existing for all existing ways to set column defaults). I guess I should address it soon in a follow-up, because particular instances of this issue keep coming up.