Default to real-utf8 when no charset is provided

ConnectionFactory.php

@@ -6,6 +6,7 @@
 use Doctrine\DBAL\Configuration;
 use Doctrine\DBAL\Connection;
 use Doctrine\DBAL\DBALException;
+use Doctrine\DBAL\Driver\AbstractMySQLDriver;
 use Doctrine\DBAL\DriverManager;
 use Doctrine\DBAL\Exception\DriverException;
 use Doctrine\DBAL\Platforms\AbstractPlatform;
@@ -43,6 +44,22 @@ public function createConnection(array $params, Configuration $config = null, Ev
 
         $connection = DriverManager::getConnection($params, $config, $eventManager);
 
+        if (! isset($params['pdo']) && ! isset($params['charset'])) {
+            $params            = $connection->getParams();
+            $params['charset'] = 'utf8';
+            $driver            = $connection->getDriver();
+
+            if ($driver instanceof AbstractMySQLDriver) {
+                $params['charset'] = 'utf8mb4';
+
+                if (! isset($params['defaultTableOptions']['collate'])) {
+                    $params['defaultTableOptions']['collate'] = 'utf8mb4_unicode_ci';
+                }
+            }
+
+            $connection = new $connection($params, $driver, $connection->getConfiguration(), $connection->getEventManager());
+        }
+
         if (! empty($mappingTypes)) {
             $platform = $this->getDatabasePlatform($connection);
             foreach ($mappingTypes as $dbType => $doctrineType) {

Tests/ConnectionFactoryTest.php

@@ -49,6 +49,26 @@ public function testContainer()
             FakeDriver::$exception = null;
         }
     }
+
+    public function testDefaultCharset()
+    {
+        $factory = new ConnectionFactory([]);
+        $params  = ['driverClass' => FakeDriver::class];
+
+        $connection = $factory->createConnection($params);
+
+        $this->assertSame('utf8', $connection->getParams()['charset']);
+    }
+
+    public function testDefaultCharsetMySql()
+    {
+        $factory = new ConnectionFactory([]);
+        $params  = ['driver' => 'pdo_mysql'];
+
+        $connection = $factory->createConnection($params);
+
+        $this->assertSame('utf8mb4', $connection->getParams()['charset']);
+    }
 }
 
 /**

UPGRADE-2.0.md

@@ -9,6 +9,8 @@ PHP and Symfony version support
    Symfony 3.4 LTS and 4.1 or newer.
  * Support for Twig 1.34 and below as well as 2.4 and below (for 2.x) releases
    was dropped.
+ * When no charset parameter is defined, it now defaults to `utf8mb4` on the
+   MySQL platform and to `utf8` on all other platforms.
 
 Commands
 --------