From f3da345bf34036f80fb30eee74ed4b3d948bf0a5 Mon Sep 17 00:00:00 2001
From: Alejandro Celaya <alejandrocelaya@gmail.com>
Date: Sat, 15 Feb 2025 11:17:14 +0100
Subject: [PATCH] Fix unique_short_code_plus_domain index in Microsoft SQL

---
 .../Core/migrations/Version20250215100756.php | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 module/Core/migrations/Version20250215100756.php

diff --git a/module/Core/migrations/Version20250215100756.php b/module/Core/migrations/Version20250215100756.php
new file mode 100644
index 00000000..77e9599e
--- /dev/null
+++ b/module/Core/migrations/Version20250215100756.php
@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ShlinkMigrations;
+
+use Doctrine\DBAL\Platforms\SQLServerPlatform;
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Fix an incorrectly generated unique index in Microsoft SQL, on short_urls table, for short_code + domain_id columns.
+ * The index was generated only for rows where both columns were not null, which is not the desired behavior, as
+ * domain_id can be null.
+ * This is due to a bug in doctrine/dbal: https://github.com/doctrine/dbal/issues/3671
+ *
+ * FIXME DO NOT DELETE THIS MIGRATION! IT IS NOT POSSIBLE TO DO THIS IN ENTITY CONFIG CODE WHILE THE BUG EXISTS
+ */
+final class Version20250215100756 extends AbstractMigration
+{
+    public function up(Schema $schema): void
+    {
+        $this->skipIf(! $this->isMicrosoftSql());
+
+        // Drop the existing unique index
+        $shortUrls = $schema->getTable('short_urls');
+        $shortUrls->dropIndex('unique_short_code_plus_domain');
+    }
+
+    public function postUp(Schema $schema): void
+    {
+        // The only way to get the index properly generated is by hardcoding the SQL.
+        // Since this migration is run Microsoft SQL only, it is safe to use this approach.
+        $this->connection->executeStatement(
+            'CREATE UNIQUE INDEX unique_short_code_plus_domain ON short_urls (short_code, domain_id);',
+        );
+    }
+
+    private function isMicrosoftSql(): bool
+    {
+        return $this->connection->getDatabasePlatform() instanceof SQLServerPlatform;
+    }
+}