MariaDb1043. Detect the need to migrate JSON columns to native JSON.

MariaDb JSON columns are marked as json with a DC2Type comment hint.

The schema manager maps such columns to a json doctrine type which
matches the metadata whether the column was declared as LONGTEXT (by the
previous MariaDb1027 platform) or JSON. This means the comparator will
not detect that a column should be upgraded from LONGTEXT to native JSON
and no migration would be generated.

Therefore, during column introspection check that the data type of the
introspected columns match that which should be set for any doctrine
types inferred from DC2Type comments. Set a flag (a platformOption
for the relevant column) where it does not.

Check whether the flag is set when the comparator diffs the expected
and actual tables and mark a column type difference where the flag is
set so a migration is generated.

Author: cgknx

src/Platforms/AbstractPlatform.php

@@ -4626,6 +4626,10 @@ public function columnsEqual(Column $column1, Column $column2): bool
             return false;
         }
 
+        if (! $this->columnDeclarationsMatch($column1, $column2)) {
+            return false;
+        }
+
         // If the platform supports inline comments, all comparison is already done above
         if ($this->supportsInlineColumnComments()) {
             return true;
@@ -4638,6 +4642,17 @@ public function columnsEqual(Column $column1, Column $column2): bool
         return $column1->getType() === $column2->getType();
     }
 
+    /**
+     * Whether the database data type matches that expected for the doctrine type for the given colunms.
+     */
+    private function columnDeclarationsMatch(Column $column1, Column $column2): bool
+    {
+        return ! (
+            $column1->hasPlatformOption('declarationMismatch') ||
+            $column2->hasPlatformOption('declarationMismatch')
+        );
+    }
+
     /**
      * Creates the schema manager that can be used to inspect and change the underlying
      * database schema according to the dialect of the platform.

src/Schema/MySQLSchemaManager.php

@@ -183,14 +183,20 @@ protected function _getPortableTableColumnDefinition($tableColumn)
         $scale     = null;
         $precision = null;
 
-        $type = $this->_platform->getDoctrineTypeMapping($dbType);
+        $type = $origType = $this->_platform->getDoctrineTypeMapping($dbType);
 
         // In cases where not connected to a database DESCRIBE $table does not return 'Comment'
         if (isset($tableColumn['comment'])) {
             $type                   = $this->extractDoctrineTypeFromComment($tableColumn['comment'], $type);
             $tableColumn['comment'] = $this->removeDoctrineTypeFromComment($tableColumn['comment'], $type);
         }
 
+        // Check underlying database type where doctrine type is inferred from DC2Type comment
+        // and set a flag if it is not as expected.
+        if ($origType !== $type && $this->expectedDbType($type, $tableColumn) !== $dbType) {
+            $tableColumn['declarationMismatch'] = true;
+        }
+
         switch ($dbType) {
             case 'char':
             case 'binary':
@@ -286,9 +292,35 @@ protected function _getPortableTableColumnDefinition($tableColumn)
             $column->setPlatformOption('collation', $tableColumn['collation']);
         }
 
+        if (isset($tableColumn['declarationMismatch'])) {
+            $column->setPlatformOption('declarationMismatch', $tableColumn['declarationMismatch']);
+        }
+
         return $column;
     }
 
+    /**
+     * Returns the database data type for a given doctrine type and column
+     *
+     * Note that for data types that depend on length where length is not part of the column definition
+     * and therefore the $tableColumn['length'] will not be set, for example TEXT (which could be LONGTEXT,
+     * MEDIUMTEXT) or BLOB (LONGBLOB or TINYBLOB), the expectedDbType cannot be inferred exactly, merely
+     * the default type.
+     *
+     * This method is intended to be used to determine underlying database type where doctrine type is
+     * inferred from a DC2Type comment.
+     *
+     * @param mixed[] $tableColumn
+     */
+    private function expectedDbType(string $type, array $tableColumn): string
+    {
+        $_type          = Type::getType($type);
+        $expectedDbType = strtolower($_type->getSQLDeclaration($tableColumn, $this->_platform));
+        $expectedDbType = strtok($expectedDbType, '(), ');
+
+        return $expectedDbType === false ? '' : $expectedDbType;
+    }
+
     /**
      * Return Doctrine/Mysql-compatible column default values for MariaDB 10.2.7+ servers.
      *

tests/Functional/Schema/MySQL/ComparatorTest.php

@@ -5,6 +5,7 @@
 use Doctrine\DBAL\Exception;
 use Doctrine\DBAL\Platforms\AbstractMySQLPlatform;
 use Doctrine\DBAL\Platforms\AbstractPlatform;
+use Doctrine\DBAL\Platforms\MariaDb1043Platform;
 use Doctrine\DBAL\Schema\AbstractSchemaManager;
 use Doctrine\DBAL\Schema\Column;
 use Doctrine\DBAL\Schema\Comparator;
@@ -147,6 +148,24 @@ public function testImplicitColumnCharset(): void
         ));
     }
 
+    public function testMariaDb1043NativeJsonUpgradeDetected(): void
+    {
+        if (! $this->platform instanceof MariaDb1043Platform) {
+            self::markTestSkipped();
+        }
+
+        $table = new Table('mariadb_json_upgrade');
+
+        $table->addColumn('json_col', 'json');
+        $this->dropAndCreateTable($table);
+
+        // Revert column to old LONGTEXT declaration
+        $sql = 'ALTER TABLE mariadb_json_upgrade CHANGE json_col json_col LONGTEXT NOT NULL COMMENT \'(DC2Type:json)\'';
+        $this->connection->executeStatement($sql);
+
+        ComparatorTestUtils::assertDiffNotEmpty($this->connection, $this->comparator, $table);
+    }
+
     /**
      * @return array{Table,Column}
      *