fixes #990: try platform detection without database name as fallback

lib/Doctrine/DBAL/Connection.php

@@ -425,9 +425,51 @@ class Connection implements DriverConnection
 
         // If not connected, we need to connect now to determine the platform version.
         if (null === $this->_conn) {
+            try {
+                $this->connect();
+            } catch (\Exception $originalException) {
+                if (empty($this->_params['dbname'])) {
+                    throw $originalException;
+                }
+
+                // The database to connect to might not yet exist.
+                // Retry detection without database name connection parameter.
+                $databaseName = $this->_params['dbname'];
+                $this->_params['dbname'] = null;
+
+                try {
                     $this->connect();
+                } catch (\Exception $fallbackException) {
+                    // Either the platform does not support database-less connections
+                    // or something else went wrong.
+                    // Reset connection parameters and rethrow the original exception.
+                    $this->_params['dbname'] = $databaseName;
+
+                    throw $originalException;
+                }
+
+                // Reset connection parameters.
+                $this->_params['dbname'] = $databaseName;
+                $serverVersion = $this->getServerVersion();
+
+                // Close "temporary" connection to allow connecting to the real database again.
+                $this->close();
+
+                return $serverVersion;
+            }
+
+        }
+
+        return $this->getServerVersion();
     }
 
+    /**
+     * Returns the database server version if the underlying driver supports it.
+     *
+     * @return string|null
+     */
+    private function getServerVersion()
+    {
         // Automatic platform version detection.
         if ($this->_conn instanceof ServerInfoAwareConnection &&
             ! $this->_conn->requiresQueryForServerVersion()

tests/Doctrine/Tests/DBAL/ConnectionTest.php

@@ -12,6 +12,7 @@ use Doctrine\DBAL\Events;
 use Doctrine\Tests\Mocks\DriverConnectionMock;
 use Doctrine\Tests\Mocks\DriverMock;
 use Doctrine\DBAL\Cache\ArrayStatement;
+use Doctrine\Tests\Mocks\VersionAwarePlatformDriverMock;
 
 class ConnectionTest extends \Doctrine\Tests\DbalTestCase
 {
@@ -712,4 +713,29 @@ class ConnectionTest extends \Doctrine\Tests\DbalTestCase
             (new Connection($this->params, $driver))->executeCacheQuery($query, $params, $types, $queryCacheProfileMock)
         );
     }
+
+    /**
+     * @group DBAL-990
+     */
+    public function testRethrowsOriginalExceptionOnDeterminingPlatformWhenConnectingToNonExistentDatabase()
+    {
+        /** @var \Doctrine\Tests\Mocks\VersionAwarePlatformDriverMock|\PHPUnit_Framework_MockObject_MockObject $driverMock */
+        $driverMock = $this->createMock(VersionAwarePlatformDriverMock::class);
+
+        $connection = new Connection(array('dbname' => 'foo'), $driverMock);
+        $originalException = new \Exception('Original exception');
+        $fallbackException = new \Exception('Fallback exception');
+
+        $driverMock->expects($this->at(0))
+            ->method('connect')
+            ->willThrowException($originalException);
+
+        $driverMock->expects($this->at(1))
+            ->method('connect')
+            ->willThrowException($fallbackException);
+
+        $this->expectExceptionMessage($originalException->getMessage());
+
+        $connection->getDatabasePlatform();
+    }
 }

tests/Doctrine/Tests/DBAL/Functional/ConnectionTest.php

@@ -4,6 +4,7 @@ namespace Doctrine\Tests\DBAL\Functional;
 
 use Doctrine\DBAL\ConnectionException;
 use Doctrine\DBAL\DriverManager;
+use Doctrine\DBAL\Platforms\AbstractPlatform;
 use Doctrine\DBAL\Types\Type;
 
 class ConnectionTest extends \Doctrine\Tests\DbalFunctionalTestCase
@@ -272,4 +273,29 @@ class ConnectionTest extends \Doctrine\Tests\DbalFunctionalTestCase
 
         $connection->close();
     }
+
+    /**
+     * @group DBAL-990
+     */
+    public function testDeterminesDatabasePlatformWhenConnectingToNonExistentDatabase()
+    {
+        if (in_array($this->_conn->getDatabasePlatform()->getName(), ['oracle', 'db2'], true)) {
+            $this->markTestSkipped('Platform does not support connecting without database name.');
+        }
+
+        $params = $this->_conn->getParams();
+        $params['dbname'] = 'foo_bar';
+
+        $connection = DriverManager::getConnection(
+            $params,
+            $this->_conn->getConfiguration(),
+            $this->_conn->getEventManager()
+        );
+
+        $this->assertInstanceOf(AbstractPlatform::class, $connection->getDatabasePlatform());
+        $this->assertFalse($connection->isConnected());
+        $this->assertSame($params, $connection->getParams());
+
+        $connection->close();
+    }
 }