Stop considering generated column definition as being its default value

src/Driver/AbstractPostgreSQLDriver.php

@@ -8,6 +8,7 @@
 use Doctrine\DBAL\Exception;
 use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\DBAL\Platforms\PostgreSQL100Platform;
+use Doctrine\DBAL\Platforms\PostgreSQL120Platform;
 use Doctrine\DBAL\Platforms\PostgreSQL94Platform;
 use Doctrine\DBAL\Platforms\PostgreSQLPlatform;
 use Doctrine\DBAL\Schema\PostgreSQLSchemaManager;
@@ -40,6 +41,10 @@ public function createDatabasePlatformForVersion($version)
         $patchVersion = $versionParts['patch'] ?? 0;
         $version      = $majorVersion . '.' . $minorVersion . '.' . $patchVersion;
 
+        if (version_compare($version, '12.0', '>=')) {
+            return new PostgreSQL120Platform();
+        }
+
         if (version_compare($version, '10.0', '>=')) {
             return new PostgreSQL100Platform();
         }

src/Platforms/PostgreSQL120Platform.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\DBAL\Platforms;
+
+/**
+ * Provides the behavior, features and SQL dialect of the PostgreSQL 12.0 database platform.
+ */
+class PostgreSQL120Platform extends PostgreSQL100Platform
+{
+    public function getDefaultColumnValueSQLSnippet(): string
+    {
+        // in case of GENERATED ALWAYS AS (foobar) STORED column (added in PostgreSQL 12.0)
+        // PostgreSQL's pg_get_expr(adbin, adrelid) will return the 'foobar' part
+        // which is not the 'default' value of the column but its 'definition'
+        // so in that case we force it to NULL as DBAL will use that column only for the
+        // 'default' value
+        return <<<'SQL'
+            SELECT
+                CASE
+                    WHEN a.attgenerated = 's' THEN NULL
+                    ELSE pg_get_expr(adbin, adrelid)
+                END
+             FROM pg_attrdef
+             WHERE c.oid = pg_attrdef.adrelid
+                AND pg_attrdef.adnum=a.attnum
+        SQL;
+    }
+}

src/Platforms/PostgreSQLPlatform.php

@@ -1193,6 +1193,19 @@ public function getTruncateTableSQL($tableName, $cascade = false)
         return $sql;
     }
 
+    /**
+     * Get the snippet used to retrieve the default value for a given column
+     */
+    public function getDefaultColumnValueSQLSnippet(): string
+    {
+        return <<<'SQL'
+             SELECT pg_get_expr(adbin, adrelid)
+             FROM pg_attrdef
+             WHERE c.oid = pg_attrdef.adrelid
+                AND pg_attrdef.adnum=a.attnum
+        SQL;
+    }
+
     /**
      * {@inheritDoc}
      */

src/Schema/PostgreSQLSchemaManager.php

@@ -616,7 +616,7 @@ protected function selectTableColumns(string $databaseName, ?string $tableName =
             $sql .= ' c.relname AS table_name, n.nspname AS schema_name,';
         }
 
-        $sql .= <<<'SQL'
+        $sql .= sprintf(<<<'SQL'
             a.attnum,
             quote_ident(a.attname) AS field,
             t.typname AS type,
@@ -632,11 +632,7 @@ protected function selectTableColumns(string $databaseName, ?string $tableName =
                 AND pg_index.indkey[0] = a.attnum
                 AND pg_index.indisprimary = 't'
             ) AS pri,
-            (SELECT pg_get_expr(adbin, adrelid)
-             FROM pg_attrdef
-             WHERE c.oid = pg_attrdef.adrelid
-                AND pg_attrdef.adnum=a.attnum
-            ) AS default,
+            (%s) AS default,
             (SELECT pg_description.description
                 FROM pg_description WHERE pg_description.objoid = c.oid AND a.attnum = pg_description.objsubid
             ) AS comment
@@ -651,7 +647,7 @@ protected function selectTableColumns(string $databaseName, ?string $tableName =
                     ON d.objid = c.oid
                         AND d.deptype = 'e'
                         AND d.classid = (SELECT oid FROM pg_class WHERE relname = 'pg_class')
-SQL;
+SQL, $this->_platform->getDefaultColumnValueSQLSnippet());
 
         $conditions = array_merge([
             'a.attnum > 0',

tests/Driver/VersionAwarePlatformDriverTest.php

@@ -15,6 +15,7 @@
 use Doctrine\DBAL\Platforms\MySQL80Platform;
 use Doctrine\DBAL\Platforms\MySQLPlatform;
 use Doctrine\DBAL\Platforms\PostgreSQL100Platform;
+use Doctrine\DBAL\Platforms\PostgreSQL120Platform;
 use Doctrine\DBAL\Platforms\PostgreSQL94Platform;
 use Doctrine\DBAL\VersionAwarePlatformDriver;
 use Doctrine\Deprecations\PHPUnit\VerifyDeprecations;
@@ -86,6 +87,7 @@ public static function postgreSQLVersionProvider(): array
             ['9.4.0', PostgreSQL94Platform::class],
             ['9.4.1', PostgreSQL94Platform::class],
             ['10', PostgreSQL100Platform::class],
+            ['12', PostgreSQL120Platform::class],
         ];
     }
 

tests/Functional/Schema/PostgreSQLSchemaManagerTest.php

@@ -5,6 +5,7 @@
 use Doctrine\DBAL\Driver\ServerInfoAwareConnection;
 use Doctrine\DBAL\Exception\DatabaseObjectNotFoundException;
 use Doctrine\DBAL\Platforms\AbstractPlatform;
+use Doctrine\DBAL\Platforms\PostgreSQL120Platform;
 use Doctrine\DBAL\Platforms\PostgreSQLPlatform;
 use Doctrine\DBAL\Schema\AbstractSchemaManager;
 use Doctrine\DBAL\Schema\Comparator;
@@ -320,6 +321,35 @@ public function testBooleanDefault(callable $comparatorFactory): void
         self::assertFalse($diff);
     }
 
+    /**
+     * @param callable(AbstractSchemaManager):Comparator $comparatorFactory
+     *
+     * @dataProvider \Doctrine\DBAL\Tests\Functional\Schema\ComparatorTestUtils::comparatorProvider
+     */
+    public function testGeneratedColumn(callable $comparatorFactory): void
+    {
+        $wrappedConnection = $this->connection->getWrappedConnection();
+        if (! $this->connection->getDatabasePlatform() instanceof PostgreSQL120Platform) {
+             self::markTestSkipped('Generated columns are not supported in Postgres 11 and earlier');
+        }
+
+        $table = new Table('ddc6198_generated_always_as');
+        $table->addColumn('id', Types::INTEGER);
+        $table->addColumn(
+            'idIsOdd',
+            Types::BOOLEAN,
+            ['columnDefinition' => 'boolean GENERATED ALWAYS AS (id % 2 = 1) STORED', 'notNull' => false],
+        );
+
+        $this->dropAndCreateTable($table);
+
+        $databaseTable = $this->schemaManager->introspectTable($table->getName());
+
+        $diff = $comparatorFactory($this->schemaManager)->diffTable($table, $databaseTable);
+
+        self::assertFalse($diff);
+    }
+
     /**
      * PostgreSQL stores BINARY columns as BLOB
      */