From 46e5b94ff54c25e514a96bbec95259e4b66e593a Mon Sep 17 00:00:00 2001
From: Allan Simon <allan.simon@supinfo.com>
Date: Thu, 19 Oct 2023 01:40:19 +0200
Subject: [PATCH] fix #6198:  stop considering generated column definition as
 being its default value

The `pg_get_expr(adbin, adrelid)` expression in Postgresql's internal table `pg_attrdef` is used to know a column definition

for most column, if this returns something, it means this column's default value. So DBAL has been considering has ALWAYS meaning it contains its default.

However for generated columns, it contains the value definition and not its default value, so we change the selectTableColumns' query to correctly set the 'default' column to `null` for generated columns

It will help setting correctly the column's attributes which in turn will help generate correct schema diff.
---
 src/Driver/AbstractPostgreSQLDriver.php       |  5 ++++
 src/Platforms/PostgreSQL120Platform.php       | 30 +++++++++++++++++++
 src/Platforms/PostgreSQLPlatform.php          | 13 ++++++++
 src/Schema/PostgreSQLSchemaManager.php        | 10 ++-----
 .../Driver/VersionAwarePlatformDriverTest.php |  2 ++
 .../Schema/PostgreSQLSchemaManagerTest.php    | 30 +++++++++++++++++++
 6 files changed, 83 insertions(+), 7 deletions(-)
 create mode 100644 src/Platforms/PostgreSQL120Platform.php

diff --git a/src/Driver/AbstractPostgreSQLDriver.php b/src/Driver/AbstractPostgreSQLDriver.php
index 099630d3368..b7e93c58bfc 100644
--- a/src/Driver/AbstractPostgreSQLDriver.php
+++ b/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();
         }
diff --git a/src/Platforms/PostgreSQL120Platform.php b/src/Platforms/PostgreSQL120Platform.php
new file mode 100644
index 00000000000..0836a0feb30
--- /dev/null
+++ b/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;
+    }
+}
diff --git a/src/Platforms/PostgreSQLPlatform.php b/src/Platforms/PostgreSQLPlatform.php
index 3364838488b..b74720145a4 100644
--- a/src/Platforms/PostgreSQLPlatform.php
+++ b/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}
      */
diff --git a/src/Schema/PostgreSQLSchemaManager.php b/src/Schema/PostgreSQLSchemaManager.php
index 13fde63b2b8..60d4ea634d6 100644
--- a/src/Schema/PostgreSQLSchemaManager.php
+++ b/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',
diff --git a/tests/Driver/VersionAwarePlatformDriverTest.php b/tests/Driver/VersionAwarePlatformDriverTest.php
index 8a84607f954..2388805112d 100644
--- a/tests/Driver/VersionAwarePlatformDriverTest.php
+++ b/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],
         ];
     }
 
diff --git a/tests/Functional/Schema/PostgreSQLSchemaManagerTest.php b/tests/Functional/Schema/PostgreSQLSchemaManagerTest.php
index 33ad395c5e8..63b25e42d69 100644
--- a/tests/Functional/Schema/PostgreSQLSchemaManagerTest.php
+++ b/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
      */