Create the default namespace in the schema

src/Tools/SchemaTool.php

@@ -6,6 +6,7 @@
 
 use BackedEnum;
 use Doctrine\DBAL\Platforms\AbstractPlatform;
+use Doctrine\DBAL\Platforms\PostgreSQLPlatform;
 use Doctrine\DBAL\Schema\AbstractAsset;
 use Doctrine\DBAL\Schema\AbstractSchemaManager;
 use Doctrine\DBAL\Schema\Index;
@@ -177,6 +178,15 @@ public function getSchemaFromMetadata(array $classes): Schema
 
         $schema = new Schema([], [], $metadataSchemaConfig);
 
+        // the platform check should be removed once the support for DBAL 3.x is dropped
+        // see https://github.com/doctrine/dbal/pull/4821, https://github.com/doctrine/dbal/pull/4831
+        if ($this->em->getConnection()->getDatabasePlatform() instanceof PostgreSQLPlatform) {
+            $defaultNamespace = $metadataSchemaConfig->getName();
+            if ($defaultNamespace !== null) {
+                $schema->createNamespace($defaultNamespace);
+            }
+        }
+
         $addedFks       = [];
         $blacklistedFks = [];
 

tests/Tests/ORM/Functional/SchemaToolTest.php

@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Doctrine\Tests\ORM\Functional;
+
+use Doctrine\DBAL\Platforms\PostgreSQLPlatform;
+use Doctrine\ORM\Tools\SchemaTool;
+use Doctrine\Tests\OrmFunctionalTestCase;
+
+class SchemaToolTest extends OrmFunctionalTestCase
+{
+    public function testValidateModelSets(): void
+    {
+        $schemaTool = new SchemaTool($this->_em);
+        $schema     = $schemaTool->getSchemaFromMetadata([]);
+        $namespaces = $schema->getNamespaces();
+
+        if ($this->_em->getConnection()->getDatabasePlatform() instanceof PostgreSQLPlatform) {
+            self::assertContains('public', $namespaces);
+        } else {
+            self::assertEmpty($namespaces);
+        }
+    }
+}