Add support for DEFAULT (expression) in table column definitions

Author: JanJakes

tests/WP_SQLite_Driver_Tests.php

@@ -11391,5 +11391,58 @@ public function testCreateTableWithDefaultNowFunction(): void {
 
 		// Verify the updated timestamp was set (should match YYYY-MM-DD HH:MM:SS format)
 		$this->assertRegExp( '/\d\d\d\d-\d\d-\d\d \d\d:\d\d:\d\d/', $result[0]->updated );
+
+		// SHOW CREATE TABLE
+		$this->assertQuery( 'SHOW CREATE TABLE test_now_default' );
+		$results = $this->engine->get_query_results();
+		$this->assertEquals(
+			implode(
+				"\n",
+				array(
+					'CREATE TABLE `test_now_default` (',
+					'  `id` int NOT NULL,',
+					'  `updated` timestamp NOT NULL DEFAULT ( now( ) ) ON UPDATE CURRENT_TIMESTAMP',
+					') ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_520_ci',
+				)
+			),
+			$results[0]->{'Create Table'}
+		);
+	}
+
+	public function testCreateTableWithDefaultExpressions(): void {
+		$this->assertQuery(
+			'CREATE TABLE t (
+				id int NOT NULL,
+				col1 int NOT NULL DEFAULT (1 + 2),
+				col2 datetime NOT NULL DEFAULT (DATE_ADD(NOW(), INTERVAL 1 YEAR)),
+				col3 varchar(255) NOT NULL DEFAULT (CONCAT(\'a\', \'b\'))
+			)'
+		);
+
+		// Insert a row and verify the default values
+		$this->assertQuery( 'INSERT INTO t (id) VALUES (1)' );
+		$this->assertQuery( 'SELECT * FROM t WHERE id = 1' );
+		$results = $this->engine->get_query_results();
+		$this->assertEquals( 3, $results[0]->col1 );
+		$this->assertStringStartsWith( ( gmdate( 'Y' ) + 1 ) . '-', $results[0]->col2 );
+		$this->assertEquals( 'ab', $results[0]->col3 );
+
+		// SHOW CREATE TABLE
+		$this->assertQuery( 'SHOW CREATE TABLE t' );
+		$results = $this->engine->get_query_results();
+		$this->assertEquals(
+			implode(
+				"\n",
+				array(
+					'CREATE TABLE `t` (',
+					'  `id` int NOT NULL,',
+					'  `col1` int NOT NULL DEFAULT ( 1 + 2 ),',
+					'  `col2` datetime NOT NULL DEFAULT ( DATE_ADD( NOW( ) , INTERVAL 1 YEAR ) ),',
+					"  `col3` varchar(255) NOT NULL DEFAULT ( CONCAT( 'a' , 'b' ) )",
+					') ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci',
+				)
+			),
+			$results[0]->{'Create Table'}
+		);
 	}
 }

wp-includes/sqlite-ast/class-wp-pdo-mysql-on-sqlite.php

@@ -5908,15 +5908,20 @@ private function get_sqlite_create_table_statement(
 				$query            .= ' PRIMARY KEY AUTOINCREMENT';
 			}
 			if ( null !== $column['COLUMN_DEFAULT'] ) {
-				// @TODO: Handle defaults with expression values (DEFAULT_GENERATED).
-
 				// Handle DEFAULT CURRENT_TIMESTAMP. This works only with timestamp
 				// and datetime columns. For other column types, it's just a string.
 				if (
 					'CURRENT_TIMESTAMP' === $column['COLUMN_DEFAULT']
 					&& ( 'timestamp' === $column['DATA_TYPE'] || 'datetime' === $column['DATA_TYPE'] )
 				) {
 					$query .= ' DEFAULT CURRENT_TIMESTAMP';
+				} elseif ( str_contains( $column['EXTRA'], 'DEFAULT_GENERATED' ) ) {
+					// Handle DEFAULT values with expressions (DEFAULT_GENERATED).
+					// Translate the default clause from MySQL to SQLite.
+					$ast            = $this->create_parser( 'SELECT ' . $column['COLUMN_DEFAULT'] )->parse();
+					$expr           = $ast->get_first_descendant_node( 'selectItem' )->get_first_child_node();
+					$default_clause = $this->translate( $expr );
+					$query         .= ' DEFAULT ' . $default_clause;
 				} else {
 					$query .= ' DEFAULT ' . $this->quote_sqlite_value( $column['COLUMN_DEFAULT'] );
 				}
@@ -6220,7 +6225,11 @@ private function get_mysql_create_table_statement( bool $table_is_temporary, str
 			) {
 				$sql .= ' DEFAULT CURRENT_TIMESTAMP';
 			} elseif ( null !== $column['COLUMN_DEFAULT'] ) {
-				$sql .= ' DEFAULT ' . $this->quote_mysql_utf8_string_literal( $column['COLUMN_DEFAULT'] );
+				if ( str_contains( $column['EXTRA'], 'DEFAULT_GENERATED' ) ) {
+					$sql .= ' DEFAULT ' . $column['COLUMN_DEFAULT'];
+				} else {
+					$sql .= ' DEFAULT ' . $this->quote_mysql_utf8_string_literal( $column['COLUMN_DEFAULT'] );
+				}
 			} elseif ( 'YES' === $column['IS_NULLABLE'] ) {
 				$sql .= ' DEFAULT NULL';
 			}

wp-includes/sqlite-ast/class-wp-sqlite-information-schema-builder.php

@@ -2096,23 +2096,22 @@ private function get_column_default( WP_Parser_Node $node ): ?string {
 		// DEFAULT (expression) - MySQL 8.0.13+ supports exprWithParentheses
 		$expr_with_parens = $default_attr->get_first_child_node( 'exprWithParentheses' );
 		if ( $expr_with_parens ) {
-			// For now, only support simple function calls like (now()), (CURRENT_TIMESTAMP)
-			// Check if it's (now()) or (NOW())
-			$now_tokens = $expr_with_parens->get_descendant_tokens( WP_MySQL_Lexer::NOW_SYMBOL );
-			if ( ! empty( $now_tokens ) ) {
-				return 'CURRENT_TIMESTAMP';
-			}
-
-			// Check if it's (CURRENT_TIMESTAMP) or (CURRENT_TIMESTAMP())
-			$current_ts_tokens = $expr_with_parens->get_descendant_tokens( WP_MySQL_Lexer::CURRENT_TIMESTAMP_SYMBOL );
-			if ( ! empty( $current_ts_tokens ) ) {
-				return 'CURRENT_TIMESTAMP';
+			$default_clause = '';
+			foreach ( $expr_with_parens->get_descendant_tokens() as $i => $token ) {
+				if ( WP_MySQL_Lexer::OPEN_PAR_SYMBOL === $token->id ) {
+					// TODO: This is just a quick fix to avoid inserting whitespace
+					//       before '(', which would break function call expressions.
+					//       The proper fix is to implement a "$node->get_bytes()" API.
+					//       This same applies to the CHECK (expression) case as well.
+					$default_clause .= $token->get_bytes();
+				} else {
+					$default_clause .= ( $i > 0 ? ' ' : '' ) . $token->get_bytes();
+				}
 			}
-
-			// For any other complex expressions, throw an exception
-			throw new Exception( 'DEFAULT values with complex expressions are not yet supported. Only (now()) and (CURRENT_TIMESTAMP) are currently supported.' );
+			return $default_clause;
 		}
-		throw new Exception( 'DEFAULT values with expressions are not yet supported.' );
+
+		throw new Exception( 'DEFAULT value of this type is not supported.' );
 	}
 
 	/**