Merge pull request #3949 from morozov/non-nullable-comments

Make table and column comments non-nullable strings

src/Platforms/AbstractPlatform.php

@@ -446,7 +446,7 @@ abstract class AbstractPlatform
     /**
      * Gets the comment of a passed column modified by potential doctrine type comment hints.
      */
-    protected function getColumnComment(Column $column) : ?string
+    protected function getColumnComment(Column $column) : string
     {
         $comment = $column->getComment();
 
@@ -1369,7 +1369,7 @@ abstract class AbstractPlatform
             foreach ($table->getColumns() as $column) {
                 $comment = $this->getColumnComment($column);
 
-                if ($comment === null || $comment === '') {
+                if ($comment === '') {
                     continue;
                 }
 
@@ -1380,18 +1380,18 @@ abstract class AbstractPlatform
         return array_merge($sql, $columnSql);
     }
 
-    protected function getCommentOnTableSQL(string $tableName, ?string $comment) : string
+    protected function getCommentOnTableSQL(string $tableName, string $comment) : string
     {
         $tableName = new Identifier($tableName);
 
         return sprintf(
             'COMMENT ON TABLE %s IS %s',
             $tableName->getQuotedName($this),
-            $this->quoteStringLiteral((string) $comment)
+            $this->quoteStringLiteral($comment)
         );
     }
 
-    public function getCommentOnColumnSQL(string $tableName, string $columnName, ?string $comment) : string
+    public function getCommentOnColumnSQL(string $tableName, string $columnName, string $comment) : string
     {
         $tableName  = new Identifier($tableName);
         $columnName = new Identifier($columnName);
@@ -1400,7 +1400,7 @@ abstract class AbstractPlatform
             'COMMENT ON COLUMN %s.%s IS %s',
             $tableName->getQuotedName($this),
             $columnName->getQuotedName($this),
-            $this->quoteStringLiteral((string) $comment)
+            $this->quoteStringLiteral($comment)
         );
     }
 
@@ -1409,13 +1409,13 @@ abstract class AbstractPlatform
      *
      * @throws DBALException If not supported on this platform.
      */
-    public function getInlineColumnCommentSQL(?string $comment) : string
+    public function getInlineColumnCommentSQL(string $comment) : string
     {
         if (! $this->supportsInlineColumnComments()) {
             throw NotSupported::new(__METHOD__);
         }
 
-        return 'COMMENT ' . $this->quoteStringLiteral((string) $comment);
+        return 'COMMENT ' . $this->quoteStringLiteral($comment);
     }
 
     /**

src/Platforms/DB2Platform.php

@@ -419,7 +419,7 @@ class DB2Platform extends AbstractPlatform
 
             $comment = $this->getColumnComment($column);
 
-            if ($comment === null || $comment === '') {
+            if ($comment === '') {
                 continue;
             }
 

src/Platforms/OraclePlatform.php

@@ -701,7 +701,7 @@ SQL
             $fields[] = $this->getColumnDeclarationSQL($column->getQuotedName($this), $column->toArray());
             $comment  = $this->getColumnComment($column);
 
-            if ($comment === null || $comment === '') {
+            if ($comment === '') {
                 continue;
             }
 

src/Platforms/PostgreSQL94Platform.php

@@ -402,7 +402,7 @@ SQL
 
             $comment = $this->getColumnComment($column);
 
-            if ($comment === null || $comment === '') {
+            if ($comment === '') {
                 continue;
             }
 
@@ -584,20 +584,6 @@ SQL
         return ['ALTER INDEX ' . $oldIndexName . ' RENAME TO ' . $index->getQuotedName($this)];
     }
 
-    public function getCommentOnColumnSQL(string $tableName, string $columnName, ?string $comment) : string
-    {
-        $tableName  = new Identifier($tableName);
-        $columnName = new Identifier($columnName);
-        $comment    = $comment === null ? 'NULL' : $this->quoteStringLiteral($comment);
-
-        return sprintf(
-            'COMMENT ON COLUMN %s.%s IS %s',
-            $tableName->getQuotedName($this),
-            $columnName->getQuotedName($this),
-            $comment
-        );
-    }
-
     public function getCreateSequenceSQL(Sequence $sequence) : string
     {
         return 'CREATE SEQUENCE ' . $sequence->getQuotedName($this) .

src/Platforms/SQLAnywhere16Platform.php

@@ -123,7 +123,7 @@ class SQLAnywhere16Platform extends AbstractPlatform
 
             $comment = $this->getColumnComment($column);
 
-            if ($comment === null || $comment === '') {
+            if ($comment === '') {
                 continue;
             }
 
@@ -320,20 +320,6 @@ class SQLAnywhere16Platform extends AbstractPlatform
         return 'TEXT';
     }
 
-    public function getCommentOnColumnSQL(string $tableName, string $columnName, ?string $comment) : string
-    {
-        $tableName  = new Identifier($tableName);
-        $columnName = new Identifier($columnName);
-        $comment    = $comment === null ? 'NULL' : $this->quoteStringLiteral($comment);
-
-        return sprintf(
-            'COMMENT ON COLUMN %s.%s IS %s',
-            $tableName->getQuotedName($this),
-            $columnName->getQuotedName($this),
-            $comment
-        );
-    }
-
     public function getConcatExpression(string ...$string) : string
     {
         return 'STRING(' . implode(', ', $string) . ')';

src/Platforms/SQLServer2012Platform.php

@@ -357,11 +357,11 @@ SQL
      * as column comments are stored in the same property there when
      * specifying a column's "Description" attribute.
      *
-     * @param string      $tableName  The quoted table name to which the column belongs.
-     * @param string      $columnName The quoted column name to create the comment for.
-     * @param string|null $comment    The column's comment.
+     * @param string $tableName  The quoted table name to which the column belongs.
+     * @param string $columnName The quoted column name to create the comment for.
+     * @param string $comment    The column's comment.
      */
-    protected function getCreateColumnCommentSQL(string $tableName, string $columnName, ?string $comment) : string
+    protected function getCreateColumnCommentSQL(string $tableName, string $columnName, string $comment) : string
     {
         if (strpos($tableName, '.') !== false) {
             [$schemaSQL, $tableSQL] = explode('.', $tableName);
@@ -474,7 +474,7 @@ SQL
 
             $comment = $this->getColumnComment($column);
 
-            if (empty($comment) && ! is_numeric($comment)) {
+            if ($comment === '') {
                 continue;
             }
 
@@ -500,11 +500,11 @@ SQL
 
             $column     = $columnDiff->column;
             $comment    = $this->getColumnComment($column);
-            $hasComment = ! empty($comment) || is_numeric($comment);
+            $hasComment = $comment !== '';
 
             if ($columnDiff->fromColumn instanceof Column) {
                 $fromComment    = $this->getColumnComment($columnDiff->fromColumn);
-                $hasFromComment = ! empty($fromComment) || is_numeric($fromComment);
+                $hasFromComment = $fromComment !== '';
 
                 if ($hasFromComment && $hasComment && $fromComment !== $comment) {
                     $commentsSql[] = $this->getAlterColumnCommentSQL(
@@ -689,11 +689,11 @@ SQL
      * as column comments are stored in the same property there when
      * specifying a column's "Description" attribute.
      *
-     * @param string      $tableName  The quoted table name to which the column belongs.
-     * @param string      $columnName The quoted column name to alter the comment for.
-     * @param string|null $comment    The column's comment.
+     * @param string $tableName  The quoted table name to which the column belongs.
+     * @param string $columnName The quoted column name to alter the comment for.
+     * @param string $comment    The column's comment.
      */
-    protected function getAlterColumnCommentSQL(string $tableName, string $columnName, ?string $comment) : string
+    protected function getAlterColumnCommentSQL(string $tableName, string $columnName, string $comment) : string
     {
         if (strpos($tableName, '.') !== false) {
             [$schemaSQL, $tableSQL] = explode('.', $tableName);
@@ -1449,7 +1449,7 @@ SQL
         return strtoupper(dechex(crc32($identifier->getName())));
     }
 
-    protected function getCommentOnTableSQL(string $tableName, ?string $comment) : string
+    protected function getCommentOnTableSQL(string $tableName, string $comment) : string
     {
         return sprintf(
             <<<'SQL'
@@ -1458,7 +1458,7 @@ EXEC sys.sp_addextendedproperty @name=N'MS_Description',
   @level1type=N'TABLE', @level1name=N%s
 SQL
             ,
-            $this->quoteStringLiteral((string) $comment),
+            $this->quoteStringLiteral($comment),
             $this->quoteStringLiteral($tableName)
         );
     }

src/Platforms/SqlitePlatform.php

@@ -514,9 +514,9 @@ class SqlitePlatform extends AbstractPlatform
         return '';
     }
 
-    public function getInlineColumnCommentSQL(?string $comment) : string
+    public function getInlineColumnCommentSQL(string $comment) : string
     {
-        if ($comment === null || $comment === '') {
+        if ($comment === '') {
             return '';
         }
 

src/Schema/Column.php

@@ -47,8 +47,8 @@ class Column extends AbstractAsset
     /** @var string|null */
     protected $_columnDefinition;
 
-    /** @var string|null */
-    protected $_comment;
+    /** @var string */
+    protected $_comment = '';
 
     /** @var array<string, mixed> */
     protected $_customSchemaOptions = [];
@@ -250,14 +250,14 @@ class Column extends AbstractAsset
         return $this;
     }
 
-    public function setComment(?string $comment) : self
+    public function setComment(string $comment) : self
     {
         $this->_comment = $comment;
 
         return $this;
     }
 
-    public function getComment() : ?string
+    public function getComment() : string
     {
         return $this->_comment;
     }

src/Schema/DB2SchemaManager.php

@@ -80,18 +80,19 @@ class DB2SchemaManager extends AbstractSchemaManager
         }
 
         $options = [
-            'length'        => $length,
-            'unsigned'      => false,
-            'fixed'         => $fixed,
-            'default'       => $default,
-            'autoincrement' => (bool) $tableColumn['autoincrement'],
-            'notnull'       => $tableColumn['nulls'] === 'N',
-            'comment'       => isset($tableColumn['comment']) && $tableColumn['comment'] !== ''
-                ? $tableColumn['comment']
-                : null,
+            'length'          => $length,
+            'unsigned'        => false,
+            'fixed'           => $fixed,
+            'default'         => $default,
+            'autoincrement'   => (bool) $tableColumn['autoincrement'],
+            'notnull'         => $tableColumn['nulls'] === 'N',
             'platformOptions' => [],
         ];
 
+        if (isset($tableColumn['comment'])) {
+            $options['comment'] = $tableColumn['comment'];
+        }
+
         if ($scale !== null && $precision !== null) {
             $options['scale']     = $scale;
             $options['precision'] = $precision;

src/Schema/MySqlSchemaManager.php

@@ -196,11 +196,12 @@ class MySqlSchemaManager extends AbstractSchemaManager
             'scale'         => $scale,
             'precision'     => $precision,
             'autoincrement' => strpos($tableColumn['extra'], 'auto_increment') !== false,
-            'comment'       => isset($tableColumn['comment']) && $tableColumn['comment'] !== ''
-                ? $tableColumn['comment']
-                : null,
         ];
 
+        if (isset($tableColumn['comment'])) {
+            $options['comment'] = $tableColumn['comment'];
+        }
+
         $column = new Column($tableColumn['field'], Type::getType($type), $options);
 
         if (isset($tableColumn['characterset'])) {

src/Schema/OracleSchemaManager.php

@@ -200,11 +200,12 @@ class OracleSchemaManager extends AbstractSchemaManager
             'length'     => $length,
             'precision'  => $precision,
             'scale'      => $scale,
-            'comment'    => isset($tableColumn['comments']) && $tableColumn['comments'] !== ''
-                ? $tableColumn['comments']
-                : null,
         ];
 
+        if (isset($tableColumn['comments'])) {
+            $options['comment'] = $tableColumn['comments'];
+        }
+
         return new Column($this->getQuotedIdentifierName($tableColumn['column_name']), Type::getType($type), $options);
     }
 

src/Schema/PostgreSqlSchemaManager.php

@@ -463,11 +463,12 @@ class PostgreSqlSchemaManager extends AbstractSchemaManager
             'fixed'         => $fixed,
             'unsigned'      => false,
             'autoincrement' => $autoincrement,
-            'comment'       => isset($tableColumn['comment']) && $tableColumn['comment'] !== ''
-                ? $tableColumn['comment']
-                : null,
         ];
 
+        if (isset($tableColumn['comment'])) {
+            $options['comment'] = $tableColumn['comment'];
+        }
+
         $column = new Column($tableColumn['field'], Type::getType($type), $options);
 
         if (isset($tableColumn['collation']) && ! empty($tableColumn['collation'])) {

src/Schema/SQLAnywhereSchemaManager.php

@@ -123,9 +123,7 @@ class SQLAnywhereSchemaManager extends AbstractSchemaManager
                 'notnull'       => (bool) $tableColumn['notnull'],
                 'default'       => $default,
                 'autoincrement' => (bool) $tableColumn['autoincrement'],
-                'comment'       => isset($tableColumn['comment']) && $tableColumn['comment'] !== ''
-                    ? $tableColumn['comment']
-                    : null,
+                'comment'       => $tableColumn['comment'] ?? '',
             ]
         );
     }

src/Schema/SQLServerSchemaManager.php

@@ -120,9 +120,12 @@ class SQLServerSchemaManager extends AbstractSchemaManager
             'scale'         => $scale,
             'precision'     => $precision,
             'autoincrement' => (bool) $tableColumn['autoincrement'],
-            'comment'       => $tableColumn['comment'] !== '' ? $tableColumn['comment'] : null,
         ];
 
+        if (isset($tableColumn['comment'])) {
+            $options['comment'] = $tableColumn['comment'];
+        }
+
         if ($length !== 0 && ($type === 'text' || $type === 'string')) {
             $options['length'] = $length;
         }

src/Schema/SqliteSchemaManager.php

@@ -12,6 +12,7 @@ use Doctrine\DBAL\Types\Type;
 use function array_change_key_case;
 use function array_reverse;
 use function array_values;
+use function assert;
 use function count;
 use function file_exists;
 use function is_string;
@@ -463,18 +464,19 @@ CREATE\sTABLE # Match "CREATE TABLE"
         return $comment === '' ? null : $comment;
     }
 
-    private function parseColumnCommentFromSQL(string $column, string $sql) : ?string
+    private function parseColumnCommentFromSQL(string $column, string $sql) : string
     {
         $pattern = '{[\s(,](?:\W' . preg_quote($this->_platform->quoteSingleIdentifier($column)) . '\W|\W' . preg_quote($column)
             . '\W)(?:\([^)]*?\)|[^,(])*?,?((?:(?!\n))(?:\s*--[^\n]*\n?)+)}i';
 
         if (preg_match($pattern, $sql, $match) !== 1) {
-            return null;
+            return '';
         }
 
         $comment = preg_replace('{^\s*--}m', '', rtrim($match[1], "\n"));
+        assert(is_string($comment));
 
-        return $comment === '' ? null : $comment;
+        return $comment;
     }
 
     private function getCreateTableSQL(string $table) : string

src/Schema/Table.php

@@ -801,7 +801,7 @@ class Table extends AbstractAsset
         return $this->trimQuotes(strtolower($identifier));
     }
 
-    public function setComment(?string $comment) : self
+    public function setComment(string $comment) : self
     {
         // For keeping backward compatibility with MySQL in previous releases, table comments are stored as options.
         $this->addOption('comment', $comment);

tests/Functional/Schema/ColumnCommentTest.php

+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\DBAL\Tests\Functional\Schema;
+
+use Doctrine\DBAL\Schema\Comparator;
+use Doctrine\DBAL\Schema\Table;
+use Doctrine\DBAL\Tests\FunctionalTestCase;
+use function array_merge;
+use function sprintf;
+
+class ColumnCommentTest extends FunctionalTestCase
+{
+    /** @var bool */
+    private static $initialized = false;
+
+    protected function setUp() : void
+    {
+        parent::setUp();
+
+        if (self::$initialized) {
+            return;
+        }
+
+        self::$initialized = true;
+
+        $table = new Table('column_comments');
+        $table->addColumn('id', 'integer');
+
+        foreach (self::columnProvider() as [$name, $type, $options]) {
+            $table->addColumn($name, $type, $options);
+        }
+
+        $this->connection->getSchemaManager()
+            ->dropAndCreateTable($table);
+    }
+
+    /**
+     * @param array<string,mixed> $options
+     *
+     * @dataProvider columnProvider
+     */
+    public function testColumnComment(string $name, string $type, array $options) : void
+    {
+        $this->assertColumnComment('column_comments', $name, $options['comment'] ?? '');
+    }
+
+    /**
+     * @return mixed[][]
+     */
+    public static function columnProvider() : iterable
+    {
+        foreach ([
+            'commented' => [
+                'string',
+                ['length' => 16],
+            ],
+            'not_commented' => [
+                'array',
+                [],
+            ],
+        ] as $typeName => [$type, $typeOptions]) {
+            foreach ([
+                'no_comment' => [],
+                'with_comment' => ['comment' => 'Some comment'],
+                'zero_comment' => ['comment' => '0'],
+                'empty_comment' => ['comment' => ''],
+                'quoted_comment' => ['comment' => "O'Reilly"],
+            ] as $caseName => $caseOptions) {
+                $name = sprintf('%s_%s', $typeName, $caseName);
+
+                yield $name => [
+                    $name,
+                    $type,
+                    array_merge($typeOptions, $caseOptions),
+                ];
+            }
+        }
+    }
+
+    /**
+     * @dataProvider alterColumnCommentProvider
+     */
+    public function testAlterColumnComment(string $comment1, string $comment2) : void
+    {
+        $table1 = new Table('column_comments');
+        $table1->addColumn('id', 'integer', ['comment' => $comment1]);
+
+        $this->connection->getSchemaManager()
+            ->dropAndCreateTable($table1);
+
+        $table2 = clone $table1;
+        $table2->getColumn('id')->setComment($comment2);
+
+        $diff = (new Comparator())->diffTable($table1, $table2);
+        self::assertNotNull($diff);
+
+        $sm = $this->connection->getSchemaManager();
+        $sm->alterTable($diff);
+
+        $this->assertColumnComment('column_comments', 'id', $comment2);
+    }
+
+    /**
+     * @return mixed[][]
+     */
+    public static function alterColumnCommentProvider() : iterable
+    {
+        return [
+            'Empty to non-empty' => ['', 'foo'],
+            'Non-empty to empty' => ['foo', ''],
+            'Empty to zero' => ['', '0'],
+            'Zero to empty' => ['0', ''],
+            'Non-empty to non-empty' => ['foo', 'bar'],
+        ];
+    }
+
+    private function assertColumnComment(string $table, string $column, string $expectedComment) : void
+    {
+        self::assertSame(
+            $expectedComment,
+            $this->connection->getSchemaManager()
+                ->listTableDetails($table)
+                ->getColumn($column)
+                ->getComment()
+        );
+    }
+}

tests/Functional/Schema/Db2SchemaManagerTest.php

@@ -4,31 +4,8 @@ declare(strict_types=1);
 
 namespace Doctrine\DBAL\Tests\Functional\Schema;
 
-use Doctrine\DBAL\Schema\Table;
-use Doctrine\DBAL\Types\BooleanType;
-
 class Db2SchemaManagerTest extends SchemaManagerFunctionalTestCase
 {
-    /**
-     * @group DBAL-939
-     */
-    public function testGetBooleanColumn() : void
-    {
-        $table = new Table('boolean_column_test');
-        $table->addColumn('bool', 'boolean');
-        $table->addColumn('bool_commented', 'boolean', ['comment' => "That's a comment"]);
-
-        $this->schemaManager->createTable($table);
-
-        $columns = $this->schemaManager->listTableColumns('boolean_column_test');
-
-        self::assertInstanceOf(BooleanType::class, $columns['bool']->getType());
-        self::assertInstanceOf(BooleanType::class, $columns['bool_commented']->getType());
-
-        self::assertNull($columns['bool']->getComment());
-        self::assertSame("That's a comment", $columns['bool_commented']->getComment());
-    }
-
     public function testListTableWithBinary() : void
     {
         self::markTestSkipped('Binary data type is currently not supported on DB2 LUW');

tests/Functional/Schema/OracleSchemaManagerTest.php

@@ -134,10 +134,10 @@ class OracleSchemaManagerTest extends SchemaManagerFunctionalTestCase
         $offlinePrimaryTable->addColumn(
             '"Id"',
             'integer',
-            ['autoincrement' => true, 'comment' => 'Explicit casing.']
+            ['autoincrement' => true]
         );
-        $offlinePrimaryTable->addColumn('select', 'integer', ['comment' => 'Reserved keyword.']);
-        $offlinePrimaryTable->addColumn('foo', 'integer', ['comment' => 'Implicit uppercasing.']);
+        $offlinePrimaryTable->addColumn('select', 'integer');
+        $offlinePrimaryTable->addColumn('foo', 'integer');
         $offlinePrimaryTable->addColumn('BAR', 'integer');
         $offlinePrimaryTable->addColumn('"BAZ"', 'integer');
         $offlinePrimaryTable->addIndex(['select'], 'from');

tests/Functional/Schema/SQLServerSchemaManagerTest.php

@@ -171,148 +171,6 @@ class SQLServerSchemaManagerTest extends SchemaManagerFunctionalTestCase
         self::assertEquals(666, $columns['df_integer']->getDefault());
     }
 
-    /**
-     * @group DBAL-543
-     */
-    public function testColumnComments() : void
-    {
-        $table = new Table('sqlsrv_column_comment');
-        $table->addColumn('id', 'integer', ['autoincrement' => true]);
-        $table->addColumn('comment_null', 'integer', ['comment' => null]);
-        $table->addColumn('comment_empty_string', 'integer', ['comment' => '']);
-        $table->addColumn('comment_string_0', 'integer', ['comment' => '0']);
-        $table->addColumn('comment', 'integer', ['comment' => 'Doctrine 0wnz you!']);
-        $table->addColumn('`comment_quoted`', 'integer', ['comment' => 'Doctrine 0wnz comments for explicitly quoted columns!']);
-        $table->addColumn('create', 'integer', ['comment' => 'Doctrine 0wnz comments for reserved keyword columns!']);
-        $table->addColumn('commented_type', 'object');
-        $table->addColumn('commented_type_with_comment', 'array', ['comment' => 'Doctrine array type.']);
-        $table->setPrimaryKey(['id']);
-
-        $this->schemaManager->createTable($table);
-
-        $columns = $this->schemaManager->listTableColumns('sqlsrv_column_comment');
-        self::assertCount(9, $columns);
-        self::assertNull($columns['id']->getComment());
-        self::assertNull($columns['comment_null']->getComment());
-        self::assertNull($columns['comment_empty_string']->getComment());
-        self::assertEquals('0', $columns['comment_string_0']->getComment());
-        self::assertEquals('Doctrine 0wnz you!', $columns['comment']->getComment());
-        self::assertEquals('Doctrine 0wnz comments for explicitly quoted columns!', $columns['comment_quoted']->getComment());
-        self::assertEquals('Doctrine 0wnz comments for reserved keyword columns!', $columns['[create]']->getComment());
-        self::assertNull($columns['commented_type']->getComment());
-        self::assertEquals('Doctrine array type.', $columns['commented_type_with_comment']->getComment());
-
-        $tableDiff                                                    = new TableDiff('sqlsrv_column_comment');
-        $tableDiff->fromTable                                         = $table;
-        $tableDiff->addedColumns['added_comment_none']                = new Column('added_comment_none', Type::getType('integer'));
-        $tableDiff->addedColumns['added_comment_null']                = new Column('added_comment_null', Type::getType('integer'), ['comment' => null]);
-        $tableDiff->addedColumns['added_comment_empty_string']        = new Column('added_comment_empty_string', Type::getType('integer'), ['comment' => '']);
-        $tableDiff->addedColumns['added_comment_string_0']            = new Column('added_comment_string_0', Type::getType('integer'), ['comment' => '0']);
-        $tableDiff->addedColumns['added_comment']                     = new Column('added_comment', Type::getType('integer'), ['comment' => 'Doctrine']);
-        $tableDiff->addedColumns['`added_comment_quoted`']            = new Column('`added_comment_quoted`', Type::getType('integer'), ['comment' => 'rulez']);
-        $tableDiff->addedColumns['select']                            = new Column('select', Type::getType('integer'), ['comment' => '666']);
-        $tableDiff->addedColumns['added_commented_type']              = new Column('added_commented_type', Type::getType('object'));
-        $tableDiff->addedColumns['added_commented_type_with_comment'] = new Column('added_commented_type_with_comment', Type::getType('array'), ['comment' => '666']);
-
-        // Add comment to non-commented column.
-        $tableDiff->changedColumns['id'] = new ColumnDiff(
-            'id',
-            new Column('id', Type::getType('integer'), ['autoincrement' => true, 'comment' => 'primary']),
-            ['comment'],
-            new Column('id', Type::getType('integer'), ['autoincrement' => true])
-        );
-
-        // Remove comment from null-commented column.
-        $tableDiff->changedColumns['comment_null'] = new ColumnDiff(
-            'comment_null',
-            new Column('comment_null', Type::getType('string'), ['length' => 255]),
-            ['type'],
-            new Column('comment_null', Type::getType('integer'), [
-                'length' => 255,
-                'comment' => null,
-            ])
-        );
-
-        // Change type to custom type from empty string commented column.
-        $tableDiff->changedColumns['comment_empty_string'] = new ColumnDiff(
-            'comment_empty_string',
-            new Column('comment_empty_string', Type::getType('object')),
-            ['type'],
-            new Column('comment_empty_string', Type::getType('integer'), ['comment' => ''])
-        );
-
-        // Change comment to empty comment from zero-string commented column.
-        $tableDiff->changedColumns['comment_string_0'] = new ColumnDiff(
-            'comment_string_0',
-            new Column('comment_string_0', Type::getType('integer'), ['comment' => '']),
-            ['comment'],
-            new Column('comment_string_0', Type::getType('integer'), ['comment' => '0'])
-        );
-
-        // Remove comment from regular commented column.
-        $tableDiff->changedColumns['comment'] = new ColumnDiff(
-            'comment',
-            new Column('comment', Type::getType('integer')),
-            ['comment'],
-            new Column('comment', Type::getType('integer'), ['comment' => 'Doctrine 0wnz you!'])
-        );
-
-        // Change comment and change type to custom type from regular commented column.
-        $tableDiff->changedColumns['`comment_quoted`'] = new ColumnDiff(
-            '`comment_quoted`',
-            new Column('`comment_quoted`', Type::getType('array'), ['comment' => 'Doctrine array.']),
-            ['comment', 'type'],
-            new Column('`comment_quoted`', Type::getType('integer'), ['comment' => 'Doctrine 0wnz you!'])
-        );
-
-        // Remove comment and change type to custom type from regular commented column.
-        $tableDiff->changedColumns['create'] = new ColumnDiff(
-            'create',
-            new Column('create', Type::getType('object')),
-            ['comment', 'type'],
-            new Column('create', Type::getType('integer'), ['comment' => 'Doctrine 0wnz comments for reserved keyword columns!'])
-        );
-
-        // Add comment and change custom type to regular type from non-commented column.
-        $tableDiff->changedColumns['commented_type'] = new ColumnDiff(
-            'commented_type',
-            new Column('commented_type', Type::getType('integer'), ['comment' => 'foo']),
-            ['comment', 'type'],
-            new Column('commented_type', Type::getType('object'))
-        );
-
-        // Remove comment from commented custom type column.
-        $tableDiff->changedColumns['commented_type_with_comment'] = new ColumnDiff(
-            'commented_type_with_comment',
-            new Column('commented_type_with_comment', Type::getType('array')),
-            ['comment'],
-            new Column('commented_type_with_comment', Type::getType('array'), ['comment' => 'Doctrine array type.'])
-        );
-
-        $this->schemaManager->alterTable($tableDiff);
-
-        $columns = $this->schemaManager->listTableColumns('sqlsrv_column_comment');
-        self::assertCount(18, $columns);
-        self::assertEquals('primary', $columns['id']->getComment());
-        self::assertNull($columns['comment_null']->getComment());
-        self::assertNull($columns['comment_empty_string']->getComment());
-        self::assertNull($columns['comment_string_0']->getComment());
-        self::assertNull($columns['comment']->getComment());
-        self::assertEquals('Doctrine array.', $columns['comment_quoted']->getComment());
-        self::assertNull($columns['[create]']->getComment());
-        self::assertEquals('foo', $columns['commented_type']->getComment());
-        self::assertNull($columns['commented_type_with_comment']->getComment());
-        self::assertNull($columns['added_comment_none']->getComment());
-        self::assertNull($columns['added_comment_null']->getComment());
-        self::assertNull($columns['added_comment_empty_string']->getComment());
-        self::assertEquals('0', $columns['added_comment_string_0']->getComment());
-        self::assertEquals('Doctrine', $columns['added_comment']->getComment());
-        self::assertEquals('rulez', $columns['added_comment_quoted']->getComment());
-        self::assertEquals('666', $columns['[select]']->getComment());
-        self::assertNull($columns['added_commented_type']->getComment());
-        self::assertEquals('666', $columns['added_commented_type_with_comment']->getComment());
-    }
-
     public function testPkOrdering() : void
     {
         // SQL Server stores index column information in a system table with two

tests/Functional/Schema/SqliteSchemaManagerTest.php

@@ -295,7 +295,7 @@ SQL;
         $sm = $this->connection->getSchemaManager();
         $sm->createTable($table);
 
-        self::assertNull($sm->listTableDetails('own_column_comment')
+        self::assertSame('', $sm->listTableDetails('own_column_comment')
             ->getColumn('col1')
             ->getComment());
     }

tests/Functional/Ticket/DBAL461Test.php

@@ -35,7 +35,6 @@ class DBAL461Test extends TestCase
             'precision' => 0,
             'autoincrement' => false,
             'collation' => 'foo',
-            'comment' => null,
         ]);
 
         self::assertInstanceOf(DecimalType::class, $column->getType());

tests/Platforms/AbstractPlatformTestCase.php

@@ -1306,7 +1306,7 @@ abstract class AbstractPlatformTestCase extends TestCase
      * @group DBAL-1176
      * @dataProvider getGeneratesInlineColumnCommentSQL
      */
-    public function testGeneratesInlineColumnCommentSQL(?string $comment, string $expectedSql) : void
+    public function testGeneratesInlineColumnCommentSQL(string $comment, string $expectedSql) : void
     {
         if (! $this->platform->supportsInlineColumnComments()) {
             self::markTestSkipped(sprintf('%s does not support inline column comments.', get_class($this->platform)));

tests/Platforms/AbstractPostgreSQLPlatformTestCase.php

@@ -347,7 +347,7 @@ abstract class AbstractPostgreSQLPlatformTestCase extends AbstractPlatformTestCa
         return [
             'ALTER TABLE mytable ADD quota INT NOT NULL',
             "COMMENT ON COLUMN mytable.quota IS 'A comment'",
-            'COMMENT ON COLUMN mytable.foo IS NULL',
+            "COMMENT ON COLUMN mytable.foo IS ''",
             "COMMENT ON COLUMN mytable.baz IS 'B comment'",
         ];
     }

tests/Platforms/AbstractSQLServerPlatformTestCase.php

@@ -662,7 +662,6 @@ abstract class AbstractSQLServerPlatformTestCase extends AbstractPlatformTestCas
     {
         $table = new Table('mytable');
         $table->addColumn('id', 'integer', ['autoincrement' => true]);
-        $table->addColumn('comment_null', 'integer', ['comment' => null]);
         $table->addColumn('comment_empty_string', 'integer', ['comment' => '']);
         $table->addColumn('comment_string_0', 'integer', ['comment' => '0']);
         $table->addColumn('comment', 'integer', ['comment' => 'Doctrine 0wnz you!']);
@@ -678,7 +677,7 @@ abstract class AbstractSQLServerPlatformTestCase extends AbstractPlatformTestCas
 
         self::assertEquals(
             [
-                'CREATE TABLE mytable (id INT IDENTITY NOT NULL, comment_null INT NOT NULL, comment_empty_string INT NOT NULL, comment_string_0 INT NOT NULL, comment INT NOT NULL, [comment_quoted] INT NOT NULL, [create] INT NOT NULL, commented_type VARCHAR(MAX) NOT NULL, commented_type_with_comment VARCHAR(MAX) NOT NULL, comment_with_string_literal_char NVARCHAR(255) NOT NULL, PRIMARY KEY (id))',
+                'CREATE TABLE mytable (id INT IDENTITY NOT NULL, comment_empty_string INT NOT NULL, comment_string_0 INT NOT NULL, comment INT NOT NULL, [comment_quoted] INT NOT NULL, [create] INT NOT NULL, commented_type VARCHAR(MAX) NOT NULL, commented_type_with_comment VARCHAR(MAX) NOT NULL, comment_with_string_literal_char NVARCHAR(255) NOT NULL, PRIMARY KEY (id))',
                 "EXEC sp_addextendedproperty N'MS_Description', N'0', N'SCHEMA', 'dbo', N'TABLE', 'mytable', N'COLUMN', comment_string_0",
                 "EXEC sp_addextendedproperty N'MS_Description', N'Doctrine 0wnz you!', N'SCHEMA', 'dbo', N'TABLE', 'mytable', N'COLUMN', comment",
                 "EXEC sp_addextendedproperty N'MS_Description', N'Doctrine 0wnz comments for explicitly quoted columns!', N'SCHEMA', 'dbo', N'TABLE', 'mytable', N'COLUMN', [comment_quoted]",
@@ -699,7 +698,6 @@ abstract class AbstractSQLServerPlatformTestCase extends AbstractPlatformTestCas
     {
         $table = new Table('mytable');
         $table->addColumn('id', 'integer', ['autoincrement' => true]);
-        $table->addColumn('comment_null', 'integer', ['comment' => null]);
         $table->addColumn('comment_empty_string', 'integer', ['comment' => '']);
         $table->addColumn('comment_string_0', 'integer', ['comment' => '0']);
         $table->addColumn('comment', 'integer', ['comment' => 'Doctrine 0wnz you!']);
@@ -716,7 +714,6 @@ abstract class AbstractSQLServerPlatformTestCase extends AbstractPlatformTestCas
         $tableDiff                                                         = new TableDiff('mytable');
         $tableDiff->fromTable                                              = $table;
         $tableDiff->addedColumns['added_comment_none']                     = new Column('added_comment_none', Type::getType('integer'));
-        $tableDiff->addedColumns['added_comment_null']                     = new Column('added_comment_null', Type::getType('integer'), ['comment' => null]);
         $tableDiff->addedColumns['added_comment_empty_string']             = new Column('added_comment_empty_string', Type::getType('integer'), ['comment' => '']);
         $tableDiff->addedColumns['added_comment_string_0']                 = new Column('added_comment_string_0', Type::getType('integer'), ['comment' => '0']);
         $tableDiff->addedColumns['added_comment']                          = new Column('added_comment', Type::getType('integer'), ['comment' => 'Doctrine']);
@@ -737,14 +734,6 @@ abstract class AbstractSQLServerPlatformTestCase extends AbstractPlatformTestCas
             new Column('id', Type::getType('integer'), ['autoincrement' => true])
         );
 
-        // Remove comment from null-commented column.
-        $tableDiff->changedColumns['comment_null'] = new ColumnDiff(
-            'comment_null',
-            new Column('comment_null', Type::getType('string'), ['length' => 255]),
-            ['type'],
-            new Column('comment_null', Type::getType('integer'), ['comment' => null])
-        );
-
         // Change type to custom type from empty string commented column.
         $tableDiff->changedColumns['comment_empty_string'] = new ColumnDiff(
             'comment_empty_string',
@@ -813,7 +802,6 @@ abstract class AbstractSQLServerPlatformTestCase extends AbstractPlatformTestCas
             [
                 // Added columns.
                 'ALTER TABLE mytable ADD added_comment_none INT NOT NULL',
-                'ALTER TABLE mytable ADD added_comment_null INT NOT NULL',
                 'ALTER TABLE mytable ADD added_comment_empty_string INT NOT NULL',
                 'ALTER TABLE mytable ADD added_comment_string_0 INT NOT NULL',
                 'ALTER TABLE mytable ADD added_comment INT NOT NULL',
@@ -822,7 +810,6 @@ abstract class AbstractSQLServerPlatformTestCase extends AbstractPlatformTestCas
                 'ALTER TABLE mytable ADD added_commented_type VARCHAR(MAX) NOT NULL',
                 'ALTER TABLE mytable ADD added_commented_type_with_comment VARCHAR(MAX) NOT NULL',
                 'ALTER TABLE mytable ADD added_comment_with_string_literal_char NVARCHAR(255) NOT NULL',
-                'ALTER TABLE mytable ALTER COLUMN comment_null NVARCHAR(255) NOT NULL',
                 'ALTER TABLE mytable ALTER COLUMN comment_empty_string VARCHAR(MAX) NOT NULL',
                 'ALTER TABLE mytable ALTER COLUMN [comment_quoted] VARCHAR(MAX) NOT NULL',
                 'ALTER TABLE mytable ALTER COLUMN [create] VARCHAR(MAX) NOT NULL',

tests/Platforms/SQLAnywhere16PlatformTest.php

@@ -136,7 +136,7 @@ class SQLAnywhere16PlatformTest extends AbstractPlatformTestCase
         return [
             'ALTER TABLE mytable ADD quota INT NOT NULL',
             "COMMENT ON COLUMN mytable.quota IS 'A comment'",
-            'COMMENT ON COLUMN mytable.foo IS NULL',
+            "COMMENT ON COLUMN mytable.foo IS ''",
             "COMMENT ON COLUMN mytable.baz IS 'B comment'",
         ];
     }
@@ -229,7 +229,7 @@ class SQLAnywhere16PlatformTest extends AbstractPlatformTestCase
         );
 
         self::assertEquals(
-            ['COMMENT ON COLUMN mytable.foo IS NULL'],
+            ["COMMENT ON COLUMN mytable.foo IS ''"],
             $this->platform->getAlterTableSQL($tableDiff)
         );
     }

tests/Schema/ColumnTest.php

@@ -55,12 +55,12 @@ class ColumnTest extends TestCase
             'unsigned' => true,
             'autoincrement' => false,
             'columnDefinition' => null,
-            'comment' => null,
+            'comment' => '',
             'foo' => 'bar',
             'bar' => 'baz',
         ];
 
-        self::assertEquals($expected, $this->createColumn()->toArray());
+        self::assertSame($expected, $this->createColumn()->toArray());
     }
 
     public function testSettingUnknownOptionIsStillSupported() : void
@@ -157,7 +157,7 @@ class ColumnTest extends TestCase
     public function testColumnComment() : void
     {
         $column = new Column('bar', Type::getType('string'));
-        self::assertNull($column->getComment());
+        self::assertSame('', $column->getComment());
 
         $column->setComment('foo');
         self::assertEquals('foo', $column->getComment());

tests/Schema/ComparatorTest.php

@@ -1236,7 +1236,7 @@ class ComparatorTest extends TestCase
      * @group DBAL-1009
      * @dataProvider getCompareColumnComments
      */
-    public function testCompareColumnComments(?string $comment1, ?string $comment2, bool $equals) : void
+    public function testCompareColumnComments(string $comment1, string $comment2, bool $equals) : void
     {
         $column1 = new Column('foo', Type::getType('integer'), ['comment' => $comment1]);
         $column2 = new Column('foo', Type::getType('integer'), ['comment' => $comment2]);
@@ -1260,17 +1260,11 @@ class ComparatorTest extends TestCase
     public static function getCompareColumnComments() : iterable
     {
         return [
-            [null, null, true],
             ['', '', true],
             [' ', ' ', true],
             ['0', '0', true],
             ['foo', 'foo', true],
 
-            [null, '', true],
-            [null, ' ', false],
-            [null, '0', false],
-            [null, 'foo', false],
-
             ['', ' ', false],
             ['', '0', false],
             ['', 'foo', false],

tests/Schema/SqliteSchemaManagerTest.php

@@ -57,7 +57,7 @@ class SqliteSchemaManagerTest extends TestCase
      * @dataProvider getDataColumnComment
      * @group 2865
      */
-    public function testParseColumnCommentFromSQL(?string $comment, string $column, string $sql) : void
+    public function testParseColumnCommentFromSQL(string $comment, string $column, string $sql) : void
     {
         $conn = $this->createMock(Connection::class);
         $conn->method('getDatabasePlatform')->willReturn(new SqlitePlatform());
@@ -76,7 +76,7 @@ class SqliteSchemaManagerTest extends TestCase
     {
         return [
             'Single column with no comment' => [
-                null,
+                '',
                 'a',
                 'CREATE TABLE "a" ("a" TEXT DEFAULT "a" COLLATE RTRIM)',
             ],
@@ -87,7 +87,7 @@ class SqliteSchemaManagerTest extends TestCase
 )',
             ],
             'Multiple similar columns with type comment 1' => [
-                null,
+                '',
                 'b',
                 'CREATE TABLE "a" (a TEXT COLLATE RTRIM, "b" TEXT DEFAULT "a" COLLATE RTRIM, "bb" CLOB DEFAULT NULL COLLATE BINARY --(DC2Type:x)
 )',
@@ -99,7 +99,7 @@ class SqliteSchemaManagerTest extends TestCase
 )',
             ],
             'Multiple similar columns on different lines, with type comment 1' => [
-                null,
+                '',
                 'bb',
                 'CREATE TABLE "a" (a TEXT COLLATE RTRIM, "b" CLOB DEFAULT NULL COLLATE BINARY --(DC2Type:x)
 , "bb" TEXT DEFAULT "a" COLLATE RTRIM',
@@ -111,14 +111,14 @@ class SqliteSchemaManagerTest extends TestCase
 , "b" TEXT DEFAULT "a" COLLATE RTRIM',
             ],
             'Column with numeric but no comment 1' => [
-                null,
+                '',
                 'a',
                 'CREATE TABLE "a" ("a" NUMERIC(10, 0) NOT NULL, "b" CLOB NOT NULL --(DC2Type:array)
 , "c" CHAR(36) NOT NULL --(DC2Type:guid)
 )',
             ],
             'Column with numeric but no comment 2' => [
-                null,
+                '',
                 'a',
                 'CREATE TABLE "b" ("a" NUMERIC(10, 0) NOT NULL, "b" CLOB NOT NULL --(DC2Type:array)
 , "c" CHAR(36) NOT NULL --(DC2Type:guid)
@@ -140,7 +140,7 @@ class SqliteSchemaManagerTest extends TestCase
                 )',
             ],
             'Column "bar", select "bar" with no comment' => [
-                null,
+                '',
                 'bar',
                 'CREATE TABLE dummy_table (
                     id INTEGER NOT NULL,
@@ -162,7 +162,7 @@ class SqliteSchemaManagerTest extends TestCase
                 )',
             ],
             'Column "bar", select "baz" with no comment' => [
-                null,
+                '',
                 'baz',
                 'CREATE TABLE dummy_table (
                     id INTEGER NOT NULL,
@@ -185,7 +185,7 @@ class SqliteSchemaManagerTest extends TestCase
             ],
 
             'Column "bar#", select "bar#" with no comment' => [
-                null,
+                '',
                 'bar#',
                 'CREATE TABLE dummy_table (
                     id INTEGER NOT NULL,
@@ -207,7 +207,7 @@ class SqliteSchemaManagerTest extends TestCase
                 )',
             ],
             'Column "bar#", select "baz" with no comment' => [
-                null,
+                '',
                 'baz',
                 'CREATE TABLE dummy_table (
                     id INTEGER NOT NULL,
@@ -230,7 +230,7 @@ class SqliteSchemaManagerTest extends TestCase
             ],
 
             'Column "bar/", select "bar/" with no comment' => [
-                null,
+                '',
                 'bar/',
                 'CREATE TABLE dummy_table (
                     id INTEGER NOT NULL,
@@ -252,7 +252,7 @@ class SqliteSchemaManagerTest extends TestCase
                 )',
             ],
             'Column "bar/", select "baz" with no comment' => [
-                null,
+                '',
                 'baz',
                 'CREATE TABLE dummy_table (
                     id INTEGER NOT NULL,